"Cannot find type" while creating a dependency graph in Visual Studio

I have a solution that consists of several projects. When I try to create a dependency graph (under the Architecture menu), I get this error:

Cannot find type [name of a perfectly good interface] in module [name of a dll].dll

I've checked that this type exists in the DLL, and other DLLs use it without a problem. Everything in my solution works fine except for the dependency graph creation. I've tried cleaning up and rebuilding multiple times, but nothing helps.

Has anyone e开发者_如何学Pythonncountered anything like this?

EDIT: I unloaded some of the projects, namely test projects, and then it worked.