Add Project gets Invalid Cast

[mbryga]

:confused: I've got a Reporting Services Data Processing Extension that concists of both Report Designer and Reporting Service components. I develop it in a solution that contains a shared DLL, the DP Extension DLL, and a test applet EXE. Everything works fine. I also have a Reporting Service project that consumes the DP Extension. If I open and run the project by itself it to works fine. However, If I try to add this project to my main solution I will get an "Invalid Cast" exception when VS.NET tries to load the project. It will fail to load, and of course their is no other information about the error. Any ideas what this is all about.