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Validation control not firing on form submit

I'm using a FormView control to allow users to insert rows to the database. I want to validate these input fields, and as such have added a regular expression validation helper. Here's the markup:
<InsertItemTemplate>
<p>
Name:
<asp:TextBox ID="NameTextBox" runat="server" Text='<%# Bind("Name") %>' />
<asp:RegularExpressionValidator ValidationExpression="^[a-zA-Z0-9 ]*$" ControlToValidate="NameTextBox" ID="NameTextBoxValidator" runat="server" ErrorMessage="Must be alphanumeric characters and spaces"></asp:RegularExpressionValidator>
</p>
<p>
Location:
<asp:TextBox ID="LocationTextBox" runat="server"
Text='<%# Bind("Location") %>' />
</p>
<p>
<asp:LinkButton ID="InsertButton" runat="server" CausesValidation="True"
CommandName="Insert" Text="Insert" />
</p>
</InsertItemTemplate>
However, when I click InsertButton the page refreshes and I get an error from SQL Server saying it can't insert a NULL value, the validator isn't getting used at all.
How can I fix this?

I assume that the user entered no text and the database does not allow null values.
A RegularExpressionValidator will not validate empty controls. So you need to provide also a RequiredFieldValidator.
The validation will not fail if the input control is empty. Use the
RequiredFieldValidator control to make the field required.
http://www.w3schools.com/aspnet/control_regularexpvalidator.asp

Not much info here, but I'll venture a guess:
Check to make sure you don't have anything happening OnLoad that's blanking things out. If you do have an OnLoad make sure it only fires when IsPostback is false.

How to align a control side-to-side?

I'm making dynamic radio buttons by using ASP.NET. Where there a validation control that I want to align side of this radios buttons.
Code:
<asp:RadioButtonList
ID="tiposeg"
runat="server"
RepeatColumns="3">
<asp:ListItem>a</asp:ListItem>
<asp:ListItem>b/asp:ListItem>
</asp:RadioButtonList>
<asp:RequiredFieldValidator ID="RequiredFieldValidator15"
ControlToValidate="tiposeg"
ErrorMessage='<% # foo.ErrorMessages.EmptyField %>'
runat="server"
/>
The problem is: if making by using <asp:RadioButtonList, the <asp:RequiredFieldValidator is displayed into next line, unlike if I do it by using "HTML pure", that is displayed side of control (without need to use CSS). I hope this is clear. Thanks in adavnce.
EDIT
in other words, it's possible put the <span> generated by asp:RequiredFieldValidator inside <table> generated by <asp:RadioButtonList?
EDIT 2
My current ASP.NET code;
<asp:RadioButtonList
ID="RadioButtonList1"
runat="server"
RepeatColumns="3">
<asp:ListItem>abcd</asp:ListItem>
<asp:ListItem>xyz</asp:ListItem>
</asp:RadioButtonList>
</li>
<li style="display:inline">
<asp:RequiredFieldValidator
ID="ReqiredFieldValidator1"
runat="server"
ControlToValidate="RadioButtonList1"
ErrorMessage="select atleast one radiobutton!"
/>
The form:
What I'm getting:
What I'm expecting:

Do you really want to arrange the radio buttons in a grid with multiple rows and columns? If not, delete the RepeatColumns attribute and add RepeatLayout="Flow" and RepeatDirection="Horizontal":
<asp:RadioButtonList runat="server" ID="RadioButtonList1"
RepeatLayout="Flow" RepeatDirection="Horizontal">
This will render the radio buttons without a containing <table>, so the validator will appear to the right of the last radio button.

Could you achieve what you want by putting the controls in DIVs and floating them both left?

How to differentiate between data posted by HTML generated by an ASP.Net Repeater Control?

So I am using a Repeater inside a form to display a list of questions that are retrieved from a database.
Each Question allows the end user to select Yes or No and add some additional Text like this.
<ItemTemplate>
<asp:Panel runat="server">
<asp:RadioButtonList RepeatDirection="Horizontal" CssClass="YesNo" ID="YesNo" runat="server">
<asp:ListItem Value="Yes" Text="Yes" />
<asp:ListItem Value="No" Text="No" />
</asp:RadioButtonList>
</asp:panel>
<asp:Panel runat="server" CssClass="MoreInfo">
<asp:TextBox ID="TextBox1" TextMode="MultiLine" Height="70px" Rows="10" Columns="25" Wrap="true" runat="server" CssClass="MoreInfoText"></asp:TextBox>
</asp:Panel>
</ItemTemplate>
The repeater is databound to a datatable in the PageLoad event.
One on the fields in the datatable is the Question's number.
So when the data is posted how can I tell which question # each answer (Yes or No and additional Text) is refering to?
If I were generating the HTML by hand instead of using a Server Control I could just make the name of the html element that will be posting data like
name=variableHoldingQuestionNumber + YesNo
name=variableHoldingQuestionNumber + AdditionalComments
But I can't seem to use a variable when setting the Name attribute inside a Repeater Item.
Is abandoning the Server Control and writing the HTML myself my only solution.

Bind the questions number to a hidden field and when the save comes back, grab that hidden field back off and take the number out of it. Then you know which question you are looking at.

Put a break point on page load and do a postback. Take a deep look at Request.Form key/value pair collection. Everything from the post will be in there, with predictable labels/indexs.

How to print a LinkButton to page?

Say I have a dynamically generated LinkButton in my ascx.cs code-behind. How could I go about "printing" this control to my page? Obviously I can't do something like just print the Text property as I need the button to retain its hyperlink. I'm guessing I want to use the WebControl.Render method, but I'm not familiar with it at all and haven't been able to find a good example of its use.

This article http://www.tomot.de/en-us/article/3/asp.net/create-a-control-in-the-codebehind-and-retrieve-its-rendered-output should explain the basics of what you are looking for.

You could provide a label at the right location in the page: <asp:Label id="myLinkButtonPlace" runat="server"></asp:Label>, and in code, you could add the linkbutton to the controlcollection of the label: this.myLinkButtonPlace.Controls.Add(aLinkButton);

Following on from #Joachim VR, there are many other asp.net controls with which you can add a dynamically created control to.
<asp:Label id="Label1" runat="server" />
<asp:PlaceHolder id="Placeholder1" runat="server" />
<asp:Panel id="Panel1" runat="server" />
The above would render HTML different.
So the Label would render as a <span id="Label1"><a></a></span>
Panel as <div id="Placeholder1"><a></a></div>
The Placeholder would simply render as the <a></a>

How to bind a classes property to a TextBox?

I have a Customer class with a string property comments and I am trying to bind it like this:
<asp:TextBox ID="txtComments"
runat="server"
TextMode="MultiLine" Text=<%=customer.Comments %>>
</asp:TextBox>
However, it gives me the error:
Server tags cannot contain <% ... %> constructs.
I also have a method in the class called GetCreatedDate and in the aspx page, I am doing
<%=GetCreatedDate()%> and <%GetCreatedDate();%>. What is the difference?

Alternatively you can set the value in the Page_Load event of the code behind file:
txtComments.Text = customer.Comments;

you should use "<%# %>" for data binding
<asp:TextBox ID="txtComments"
runat="server"
TextMode="MultiLine" Text="<%# customer.Comments %>">
</asp:TextBox>

Try this instead.
<asp:TextBox ID="txtComments"
runat="server"
TextMode="MultiLine" Text=<%# customer.Comments %>>
</asp:TextBox>
Notice the = to #

Use the DataBinding syntax as stated, <%# customer.Comments %>. This syntax is only evaluated when the TextBox is databound. You would usually use it in a DataBound list. In this case you need to databind the control manually. Override the page's OnDataBinding method and call txtComments.DataBind();
The databinding syntax is the only way to declaratively set ServerControl properties from the aspx page. The Response.Write of the other syntax happens at a time that the ServerControl properties cannot be accessed. If the control is not inside a databound control, you have to databind it.
If you were looking to go all declarative in your page, you don't gain to much using this method because you still need to write code in the code behind.
An alternative if you want to use the TextBox on its own without a parent DataBound control would be to subclass the TextBox, add an AutoBind property, and in the subclassed control call its DataBind method if it is true. That would let you bind the values without writing databinding code in the code behind.
You could also add the TextBox and other form controls to a FormView control and bind it to your object. You can still use the DataBinding syntax in that case.

try this
<asp:TextBox ID="txtComments"
runat="server"
TextMode="MultiLine" Text='<%# customer.Comments %>'>
</asp:TextBox>