I've got a DLL in C# that targets the 4.0 framework. I have a managed C++ dll that also targets the 4.0 framework, but when I try to add my C# dll as a reference, I get 'Could not add a reference to file MyFile.dll because it is neither a .NET assembly nor a registered ActiveX control'.
This works fine if both DLL's target 4.5. I am using VS2012. I want to be able to target 4.0 though, not 4.5.