The type or namespace name could not be found [duplicate]

Question

I have a C# solution with several projects in Visual Studio 2010. One is a test project (I'll call it "PrjTest"), the other is a Windows Forms Application project (I'll call it "PrjForm"). There is also a third project referenced by PrjForm, which it is able to reference and use successfully.

PrjForm references PrjTest, and PrjForm has a class with a using statement:

using PrjTest; 

1. Reference has been correctly added
2. using statement is correctly in place
3. Spelling is correct
4. PrjTest builds successfully
5. PrjForm almost builds, but breaks on the using PrjTest; line with the error:

The type or namespace name 'PrjTest' could not be found (are you missing a using directive or an assembly reference?)

I've tried the following to resolve this:

1. Removed Resharper (since Resharper had no trouble recognizing the referenced project, I thought it might be worth a shot)
2. Removed and re-added the reference and using statement
3. Recreated PrjForm from scratch
4. PrjForm currently resides inside the PrjTest folder, I tried moving it to an outside folder
5. Loaded the solution on a different computer with a fresh copy of VS 2010

I have done my homework and spent far too long looking for an answer online, none of the solutions has helped yet.

What else could I try?

Answer 1

See this question.

Turns out this was a client profiling issue.

PrjForm was set to ".Net Framework 4 Client Profile" I changed it to ".Net Framework 4", and now I have a successful build.

Thanks everyone! I guess it figures that after all that time spent searching online, I find the solution minutes after posting, I guess the trick is knowing the right question to ask..