Inherit from abstract user control breaks designer view

[David Crandall]

Hey,

I've created an abstract class that inherits from System.Web.UI.UserControl. When I create an implementation of this class I can no longer use the Design View in Visual Studio.Net. For Example

//Abstract base class
public abstract class ReportPanel : System.Web.UI.UserControl
{
public abstract void DisplayReport();
}

//Implementation code class
public UsageReport : ReportPanel
{
public void DisplayReport(){
//Implementation of required method
}
}

//ascx file @Control directive
<%@ Control language="c#" Codebehind="UsageReport.ascx.cs" AutoEventWireup="false" Inherits="UsageReport" %>

If I try to go to the design view of the ascx file in VS.Net I get the following error:

The file could not be loaded into the web forms designer. Please correct the following error and then try loading it again:

Type Abstract

Make sure all of the classes used in the page are built or referenced in the project....

The page runs without error but I can no longer use the Design View.

Any suggestions?