Debugging Custom Extensions with Visual Studio 2010

If you are developing custom extensions for Reporting Services with Visual Studio 2010, you have to make sure you compile the extension for the .NET 2.0/3.5 CLR because current versions of Reporting Services run in the 2.0/3.5 CLR, and extensions compiled for .NET 4.0 cannot be loaded into the 2.0/3.5 CLR.