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The name "ImageViewModel" does not exist in the namespace "clr-namespace:AdminControlCenter.ViewModel"

As the titel say i have the problem that Xaml don´t now my clr namespace, I read the other posts and tried their solution without any success, I rebuild, Start as Admin tried the build conviguration etc.
My Project looks so:
My XAML:
<Controls:MetroWindow x:Class="AdminControlCenter.View.MainView"
xmlns:Controls="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:resx="clr-namespace:AdminControlCenter.Properties;assembly=AdminControlCenter"
xmlns:local="clr-namespace:AdminControlCenter;assembly=AdminControlCenter"
xmlns:vm="clr-namespace:AdminControlCenter.ViewModel;assembly=AdminControlCenter"
Title="MainWindow" Height="400" Width="600">
<Grid VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Background="White">
<Grid.DataContext>
<vm:ImageViewModel x:Name="imageViewModel"/>
</Grid.DataContext>
And the Error:
And the ImageViedModel:
namespace AdminControlCenter.ViewModel
{
public class ImageViewModel : ViewModel
{
public ImageViewModel()
{
}
.....
The classes are public and show up at the autoformat, when I type for example
"vm:" It also go to the Definition of the Class by using F12.
When I use some MVVM tutorial tests, they are working. But when I try in my Project all ViewModels are not found.
Why doesen´t found the XAMl my ViewModels ?
Edit:
I tried every variation of the assemblies with and without, I also try to delete the suo and try every build configuration, and I restart VS as Admin etc. I also make a new Project with another name and rewrite all classes (Not Copied them) also without any success

I get this error too sometimes, but I can build/deploy anyway.. I think it's a Visual Studio bug.. Are you able to deploy your solution?
Maybe you can try to copy Model and ViewModel's content somewhere else , delete from the project these two files and recreate the files again.. Or.. Do you know how to use the ViewModelLocator class? Since I started use it I never seen that issue again
See here for details about ViewModelLocator: link

XAML Converter in different namespace

I'm developing a c# Windows Phone 8.1 App in VC2013 and stumbled over an odd issue.
To make my Code more 'clean', I decided to put different parts of my App into different folders. There is no problem with calling XAML pages from these folders in the c# code.
BUT I seem to have issues linking these folders in XAML Code itself. For example I have following structure:
root, Files: App.cs+xaml, Mainpage.cs+xaml
|
-- Folder: Login
|
-- Files: LoginPage.cs+xaml
-- Folder: Converters
|
-- Files: converterClass.cs
To use the IValueConverter from the converterClass.cs like I always did, I put the following in the Header of my XAML file:
<Page
x:Class="myApp.Login.LoginPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:meinStundenplaner.Login"
xmlns:myConverter="using:myApp.Converters"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Page.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="../Styles/standardStyles.xaml"/>
</ResourceDictionary.MergedDictionaries>
<myConverter:DateTimeConverter x:Key="DateTimeConverter" />
... some more converters
</ResourceDictionary>
</Page.Resources>
...
Now it happens, that if I type <myConverter: the autocomplete does find my converter classes like usually, but when compiling (it is compiling) and testing on device none of the converters works and also I get an error in the Error-list saying
The name 'DateTimeConverter' in namespace 'using:myApp.Converters' does not exist.
Where did I go wrong?

wow ... after using VS2015 and the same error persisted, I played a little bit around with settings and stuff.
I kept being curious, why it would compile and deploy even it triggered so many errors. The problem appeared to be inconsistent.
The solution was different than expected:
You have to set Solution Platforms to x86 instead of ARM (which I needed to deploy on device). Luckily VS2015 has this option in a handy shortcut, what you can't say about VS2013.
Nevertheless it's solved...

DataContext is not bind in the XAML file

I am new to WPF + MVVM architecture. In my application, I am trying to implement "DataContext" in the XAML itself as below
<Window x:Class="MyWPF.UI.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vm="clr-namespace:MyWPF.UI.ViewModel"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<vm:Northwind_DataViewModel></vm:Northwind_DataViewModel>
</Window.DataContext>
<Grid>
</Grid>
</Window>
I am getting "The name 'Northwind_DataViewModel' does not exists in the namespace 'clr-namespace:MyWPF.UI.ViewModel".
I have ViewModel file. Before using "DataContext", I built this application.
Could you please let me know what is wrong with my code?
thanks

The name 'Northwind_DataViewModel' does not exists in the namespace 'clr-namespace:MyWPF.UI.ViewModel".
Chances are, you compiler is right. There is no class named MyWPF.UI.ViewModel.Northwind_DataViewModel in your project. Make sure it exists, has a public, parameterless constructor, is not an inner class of something and not generic. If that's the case, it will work.

In case namespace is declared in separate assembly from where your XAML resides, you have to provide assembly name as well.
Sample:
xmlns:sys="clr-namespace:System;assembly=mscorlib"
Similarly, provide your assembly name where this namespace resides (Assuming assembly name is MyWPF.UI):
xmlns:vm="clr-namespace:MyWPF.UI.ViewModel;assembly=MyWPF.UI"

Thanks a lot your responses. Finally I got the solution. Actually, this project was placed in a shared folder. So, I moved it to my local drive (C:). Now, it is working fine without any issues.
I guess, in shared path / shared folder, it may not work. Please let me know if I am wrong.
thanks again.

In order to solve this problem, you need to understand how the DataContext works. This answer contains a lot of hints and links to supporting tutorials:
ReSharper WPF error: "Cannot resolve symbol "MyVariable" due to unknown DataContext"

TextBox custom control header problems

I'm currently trying to use this TextBox AutoComplete custom control :
http://www.codeproject.com/Articles/26535/WPF-Autocomplete-Textbox-Control?msg=3484969#xx3484969xx
This is the first time I'm adding such external things in my project and when I add the header line in my Xaml file like explained in the article :
<UserControl x:Class="Maha.Gestion.Note_de_frais.SaisieNoteDeFrais"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
xmlns:local="clr-namespace:WPFAutoCompleteTextbox"
>
VisualStudio tell me that clr-namespace is not included in the assembly.
I'm sure this is something totally trivial but after few hours still can't find any solution.
All files asked by the author of the article has been added of course.
Someone can explain me the good way to add such external resources ?
Thanks

xmlns stands for XML NameSpace. It basically links a prefix of your choice to a namespace. In your case, it links the local prefix with the namespace declared in the file that you want to use.
You can find out more by looking at the XAML Namespaces and Namespace Mapping for WPF XAML article at MSDN.
Please check that the file that you want to use has this exact namespace declared.
Please remove all white space from your xmlns declarations - you may have extraneous characters hidden there.
Like this:
xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"
xmlns:local="clr-namespace:WPFAutoCompleteTextbox">

Visual Studio refactor-rename causes inexplicable global replace of attributes in XAML file

I feel like I must be going crazy, but I just changed the name of a property in a view model (a C# file) from Width to Size using Visual Studio's refactor-rename feature. When I was done, this error appeared in the Error window:
Error 2: The property 'Size' does not exist in XML namespace 'http://schemas.microsoft.com/winfx/2006/xaml/presentation'.
The error was referring to a XAML UserControl file. When I checked the file to see what was up, I realized that every attribute named Width had been changed to Size.
Example:
<UserControl x:Class="ApbSymbolGenerator.Views.Symbol"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
Size="{Binding Size}"
Height="{Binding Size}">
This is the first time I've ever had refactor-rename cause a change to a XAML file (besides the x:class value). (Note: I did not do a global find/replace, I did refactor-rename. I undid everything and performed the rename again, and it did the same thing.)
Strangely, it only affected one of several XAML files in my app that has a Width property.
Any explanation what could be going on here?

Looks like this is a bug (that won't be fixed) - Refactor Rename Bug