Visual Studio saying name doesn't exist in current context

Question

I am calling a static method on a class like

Foo.bar() 

Visual studio's intellisense recognizes Foo and autocompletes bar for me (it highlights Foo and everything like it is working fine). Everything looks fine until I go to build the project, and it throws an error saying the name Foo doesn't exist in current context.

I am using this static method call in other files, so I know the class is ok. The situation is too big to post code, so I am mostly looking for reasons to start looking into that would cause intellisense to function normally but get errors on compile like this.

Answer 1

I've seen this error caused by differing versions of the .NET framework in the different projects. The Class Library I built was 4.5 and the application was 4.0, but the only error it gave was namespace errors. Changing the framework version on the class library and rebuilding it, then the application, resolved the error.