I have builded a web application use ASP.NET(VB)¡£<BR>here is the problem:<BR>in file pBase.vb<BR> Namespace InfoEx<BR> Public Class pBase<BR> Inherits System.Web.UI.Page<BR> ...<BR> End Class<BR> End Namespace<BR><BR>In file test.aspx.vb(code-behind file of test.aspx)<BR> Namespace InfoEx<BR> Public Class test<BR> Inherits pBase<BR> ...<BR> End Class<BR> End Namespace<BR>there is an error every time i open file test.aspx:<BR>"The file failed to load in the Web Form designer.Please correct the following error, then load it again: An exception occurred while trying to create an instance of InfoEx.pBase. The exception was "Object refrence not set to an instance of an object.". "<BR>Anyone can help??<BR>