.NET 3.0 Unit Testing getting System.MethodAccessException calling .NET 2.0

Is there any way to get around this exception? Can I not call a .NET 2.0 from 3.5? I have to write .NET 2.0 to maintain capability with BizTalk 2006/R2. But I would like to test with VS2008 Unit Tests to be consistent to other non-BizTalk code that we are testing.

Test method ABC.UnitTest.UnitTest1.TestReferenceCode1 threw exception: System.MethodAccessException: ABC.EasyRegEx.e开发者_开发技巧xtractUsingRegEx(System.String, System.String).

Nevermind - I had a deep function somewhere in the GAC that had a method changed from private to public. It was using the GAC version instead of the local version.