Thread: Unknown Server Tag for Custom Control - Visual Studio 2010

While working on my first project with Visual Studio 2010, i had to go through some weird stuffs as I tried to convert a Website project to a Website Application project.

One of the problems was with custom controls.
Here is the sample code in C# of a custom control I used for that project.

namespace CustomControls
{
public class MyTextArea : TextBox
{
//----------code here
}
}

On web.cinfig I added
<pages>
<controls>
<add tagPrefix="cc" namespace="CustomControls"/>
</controls>
</pages>

On a page I use the control like this:
<cc:MyTextArea ID="test" runat="server">
</cc:MyTextArea>

It compiles fine without any error. However when I view the page on browser I get the error:
Unknown Server Tag cc:MyTextArea

Note that this code worked fine in both visual studio 2005, and visual studio 2008.

Solution:
Apparently I would need to add the assembly reference on web.config
<pages>
<controls>
<add tagPrefix="cc" namespace="CustomControls" assembly="MyProjectName" />
</controls>
</pages>

That control inherits the DropDownList control For some reason it is never added to the designer and visual studio never really recognizes it.Thanks for sharing information.