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The type or namespace name 'Device' does not exist in the namespace 'System'

I am trying to work with GeoCoordinate which is meant to be supported by .Net Framework 4.5. I am working on winodws 8 and I have .Net Framework 4.5, but I keep getting The type or namespace name 'Device' does not exist in the namespace 'System' error.
Any solution?

The type or namespace name 'XXX' could not be found...
Always bear in mind, if you get this error there are three possibilities.
You missed the using directive.
You missed the Assembly reference
You have "using directive" as well as "Assembly reference" in place but the current project's target framework version is lower than the referenced assembly target framework version.
Almost all the cases above three steps should solve the problem.
Hope this helps.

Does not have added reference of System.Device dll in your project.
Steps to Add Reference.
1. Right click on the Reference folder on your project.
2. Select Add Reference.
3. Expand Assemblies option.
4. Search System.Device in the serach box at right corner side.
5. After searching, click on checkbox to select and click on ok.

If you are using VS.NET:
Right click on the References folder on your project.
Select Add Reference.
Select the .NET tab (or select the Browse button if it is not a .NET Framework assembly).
Double-click the assembly containing the namespace in the error message.
Press the OK button.
If you are using the command line, use the /r: or /reference: option. For Example:
csc.exe /reference:System.Drawing.dll MyFontDisplayApp.cs
When you recompile, this error will no longer appear.

It is also possible that your project uses x64 libraries and your machine has limited x64 libraries. I think this happened in my case.
Possible Solution: I copied library from x86 folder to bin folder of my project. Then added the new reference(discard the old reference to same library). AND IT WORKED.
Note: Please correct me if I am wrong here.

Visual Studio 2010 removes reference upon compiling [duplicate]

I'm working on a C# 4.0 project in VS2010 and needed to use some older DLLs containing controls that were created in C# 3.5 on VS2008. When I first add the DLLs to the references, I was able to see the namespace via intellisense and create an instance of one of the controls, but when I go to build, it gives me the following error:
The type or namespace name 'BCA' could not be found (are you missing a using directive or an assembly reference?)
And I do have a using directive for that namespace already, which is now underlined in red, showing that VS cannot find it. And now, intellisense won't pick up that namespace at all.
I even tried added the controls to the toolbox (which worked) but then when I drag them to the GUI, it says that it cannot locate the DLL reference, even though it obviously knows where it is.
I even tried changing the target framework to 3.5, but still with the same results.
Any thoughts as to why this could be happening?
Edit - I've notice that in the csc.exe arguments that VS outputs, it does not have any /reference entries for the DLLs I'm trying to use. When I create the same basic project in VS2008, those entries exist. Also, I can successfully reference the DLLs in a DLL project in VS2010... it seems to just be WinForms projects that don't work.

Turns out that it was something to do with VS2010 defaulting to the .NET 4 client profile, as soon as I changed it to the regular profile it built fine. There's a day wasted...

view the target framework.. in my project, was 4.0 client profile, e the reference dll was in 4.0

I tried Build->Clean Solution and then could add the reference.

I used to have similar problem, but the profiles were not the issue, so the problem was that my class library use a special NuGet package that has Dependency... so I install the dependency package in the target project and added the project reference and works!
But I am not sure if there is a better solution for this problem??? for me VS should be smart enough to carry those dlls along with the references. (I already verified that "Copy Local" is set to True)

Missing System.Windows

I have a rather large solution with some Silverlight and WPF projects inside it, as well as some class libraries and other things.
One of the project is a class library that references a SilverLight application which references System.Windows
But at runtime, I get the error:
{"Could not load file or assembly 'System.Windows, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e' or one of its dependencies. The system cannot find the file specified.":"System.Windows, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e"}
I looked in the GAC (C:\Windows\assembly) and couldnt see it in there...
Whats happening here?
The reference is to: c:\Program Files\Reference Assemblies\Microsoft\Framework\Silverlight\v4.0\System.Windows.dll which DOES exist.

Sounds to me like your WPF app is loading a class library that references a Silverlight assembly. That cannot work, cats and dogs. If an assembly is referenced by both a WPF and a Silverlight app then it has to be compiled twice with different framework assembly references. That takes two projects. Keeping the WPF and the Silverlight stuff separate in different solutions is the best way to keep out of trouble.

I've seen similar errors in two cases that might apply here:
When an assembly I reference required an assemble I have not referenced . . . in this case that would mean System.Windows is using something else you need to add a reference too.
The more interesting case is when VS2010 auto selected ".Net Framework 4 Client Profile" for me when I actually needed ".Net Framework 4" (no "client profile"). Select the project properties and see what your setting is.
Frank
Per you request additional instructions:
Open Solution in VS2010, right click the project in question (not the solution line) and select "properties" from the bottom. In the resulting GUI, select the "Application" tab and make sure "Target Framework" does not have "client profile" in the name . . . that is should be ".NET Framework 4" not ".NET Framework 4 Client Profile".

I have not found this solution anywhere else, but stumbled upon it as a trial-and-error-by-fire...
The error message was a bit misleading in my situation. The tip off was that it wasn't really the "System.Windows" assembly itself, but one of the dependant assemblies.
What you may want to do is to check your GAC and see if one of these assemblies are in it:
System.Windows
System.Windows.Controls
System.Windows.Controls.Toolkit
System.Windows.Controls.Layout.Toolkit
Try removing them from just the GAC, then do your rebuild. If it doesn't work, just open two windows explorer windows and copy them back from either the c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\Silverlight\v4.0\System.Windows.dll folder or the folder for your Silverlight Toolkit and you'll be back to where you started from.
Here's what I suspect is happening:
The Visual Studio 2010 compiler is getting confused about where to get those referenced assemblies when doing the build because the GAC assemblies always takes precedence over another copy of an assembly (even the reference assembly folder that VS2010 uses). So even though the assembly is technically correct with the same ID key and everything there's something with the VS2010 compiler that can't determine which library to use for building and it will refuse to complete the build.

mmmm sometimes you put your classes in different project for example you can create a project for viewmodels , if is this the case then you need to reference PresentationCore.dll , this is the dll that give you access to System.windows so you can use ICommand for command bindings

Cannot use external references with C# Console Application

I have tried all the suggestions below but still no joy.
I'm now trying a console application, and let me explain exactly what I'm doing.
I create a new console project in VS 2010
I add a number of references (dll's) some that aren't mine such as Castle.Winsor and N2 CMS dlls
in the console app I can add using statements indicating I am using name spaces within the referenced DLLs
I start writing code.
As soon as I compile all the code that uses the referenced DLLs immediately complains with "The type or namespace name '' could not be found (are you missing a using directive or an assembly reference?)"
I have tried setting the dlls to copy to local always, I have copied the DLL into the same directory, I have tried added reference by project and adding a reference to the DLL's themselves
I don't get this problem with a web application project or a ASP.net project they always work fine, only something that is compiled to an EXE like a console app or windows service.
there must be something I'm missing or I would have got this working by now.

Change the project Target to a non Client Profile target. Right click the Project and select Properties, you should see a list of Framework versions. As you are using VS2010, the Console project you've created by default targets .NET Framework 4.0 Client Profile, change that to .NET Framework 4.0.

Check if Copy Local is set to true for the referenced assembly.

First, as to your question, its hard to know exactly what you're doing wrong, but from the fact that you're using an underscore in an assembly name (and probably in namespaces and type names), it suggests you're rather new to the .NET world.
This suggests that you're adding references to other projects in your solution by browsing to the compiled assembly, rather than by adding a Project Reference. When adding a reference, you must select the Project tab rather than browsing for the assembly.
Even if you don't believe this is the issue, remove all references and re-add project references to make absolutely sure. Assumption, asses etc.
Once you've done that, I'd strongly suggest remove all the underscores from your types, namespaces and assemblies. You might want to go read the framework design guidelines, too.

Open your .Proj(Windows service project file) file in notepad and check whether your assembly location(data_object) is the same which you are pointing.
When you open .Proj file in notepad you can check for,
Project reference,
<ProjectReference Include="C:\StackOverflow\StackOverflow.csproj">
And if you giving dll or exe refrence then
<Reference Include="StackOverflow, Version=1.0.0.0, Culture=neutral, processorArchitecture=x86">
<SpecificVersion>False</SpecificVersion>
<ExecutableExtension>.exe</ExecutableExtension>
<HintPath>C:\StackOverflow\bin\Debug\StackOverflow.exe</HintPath>
</Reference>
I suggest you to give exact location including drive name like above example.
Other option you may try,
1. Clean and rebuild
2. Add Project reference if you already tried dll reference
3. Check whether the folder (referred assembly location) is Read Only then remove it.

In VS 2019, I had two projects, one C++ and other one C# Console in one solution file. When tried to add a dll reference through "Add reference", I was not able to see Browse button in "Reference Manager" window, to select dll file.
But when I created only C# Console app inside solution then I could add dll reference.

Reference DLLs not loading in Visual Studio 2010

I'm working on a C# 4.0 project in VS2010 and needed to use some older DLLs containing controls that were created in C# 3.5 on VS2008. When I first add the DLLs to the references, I was able to see the namespace via intellisense and create an instance of one of the controls, but when I go to build, it gives me the following error:
The type or namespace name 'BCA' could not be found (are you missing a using directive or an assembly reference?)
And I do have a using directive for that namespace already, which is now underlined in red, showing that VS cannot find it. And now, intellisense won't pick up that namespace at all.
I even tried added the controls to the toolbox (which worked) but then when I drag them to the GUI, it says that it cannot locate the DLL reference, even though it obviously knows where it is.
I even tried changing the target framework to 3.5, but still with the same results.
Any thoughts as to why this could be happening?
Edit - I've notice that in the csc.exe arguments that VS outputs, it does not have any /reference entries for the DLLs I'm trying to use. When I create the same basic project in VS2008, those entries exist. Also, I can successfully reference the DLLs in a DLL project in VS2010... it seems to just be WinForms projects that don't work.

Turns out that it was something to do with VS2010 defaulting to the .NET 4 client profile, as soon as I changed it to the regular profile it built fine. There's a day wasted...

view the target framework.. in my project, was 4.0 client profile, e the reference dll was in 4.0

I tried Build->Clean Solution and then could add the reference.

I used to have similar problem, but the profiles were not the issue, so the problem was that my class library use a special NuGet package that has Dependency... so I install the dependency package in the target project and added the project reference and works!
But I am not sure if there is a better solution for this problem??? for me VS should be smart enough to carry those dlls along with the references. (I already verified that "Copy Local" is set to True)