VS2010 Console application add reference issues

Question

I have a solution with multiple class libraries and a console application. When I add a reference to the other projects in my console app the reference namespaces and classes appear fine. However when I attempt to build the project the referenced namespaces are no longer valid. The reference still appears in the Reference folder in the console app. Any ideas on what i'm doing wrong?

Answer 1

I found the solution at the link below. Turns out it was a project configuration issue. It was targeting .NET Framework 4.0 Client Profile.

Cannot use external refernces with C# Console Application

Answer 2

You have a build error in one of the other projects.