VSPackage problem, how to troubleshoot file.myproj is not supported by this version of application

I have an Isolated Shell application with a Package that has project type definedusing MPF Framework. When I click File - New I do see my template but when I hit OK, it gives me the error message

   C:\Path\To\project.myproj cannot be opened because project type (.myproj) is not supported by this version of the application.

 I have the Project related attributes added to my Package class. How do I troubleshoot this ?

Thanks

Fahad