Link to C # project recognized by Ide, but will not build

Question

I created the project links in one C # 4.0 project to another C # 4.0 project in the same solution.

They are both exe projects.

when I add the link, the smart system starts collecting all the classes in the specified project. However, when I switch to compilation, I get the following error: "Type or namespace name" ... "could not be found (do you miss the using directive or assembly references?)". And then all class names lose their blue color and are underlined in red.

Answer 1

• Right click on Project Properties
  • Check target structure
  • If this is a .net Framework 4.0 Client profile, not a change to its .net Framework 4.0