Hello,
You probably have both VS 2005 and VS2008 installed on your system and have the VWG SDK of both Net2.0 and Net3.5.
You need to amke sure that the DLLs you are referencing in the Visual WebGui Application project, are the ones of the correct Net version. As you are using VS 2008 in your example, you need to have Net3.5 assemblies the version of which should be 3.0.5701.0.
Regards,
Ori Cohen
Manager of support, the Visual WebGui team