如何使Visual Studio 2008对象测试台工作？

I'd like to use the Object Test Bench in VS2008. The docs - and even the helpful text in the test bench window - say to right click on class in the Class View. Further reading indicates that this class must be in the startup project or referenced assembly. I've tried this on numerous classes - public, private, static, you name it - in several assemblies (either the startup project or a referenced project), and the context menu item "Create Instance" never appears.I'd like to use the Object Test Bench in VS2008