Hey,

System.Web.UI.Design is within the System.Design.dll assembly, you have to add that to your references list; The UITypeEditor is defined in System.Drawing.Design, you may have to add that dll as well... but maybe not. I'm not sure if that is in the same assembly (System.Design.dll).

Brian

Brian,

   Thats true, i needed to add the System.Design.Dll reference. The UITypeEditor issue is now resolved. However the error "specified cast is not valid" still appears as before.