无法在asp.net MVC中引用类库

Question

I do this lesson from: http://www.codeproject.com/Articles/1010152/Learn-MVC-Project-in-Days-Day I'am at the end lab 32. I did everything step by step but I have this error:

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

When I add any reference to WebApplication1 I see BusinessEnties or ViewModel and I have no errors but when I build this errors back.

UPDATED

My class tree:

And dependecy map

Answer 1

Check your projects .Net versions. If the MVC Project has a lesser version then the class Library it most likely won't work.

Answer 2

确保课程是公开的