How to add dll in c# project

Question

I am trying to add a [Science.dll] in my project which should be staright forward. But I am getting a problem. Can someone tell me why?

My C# projec

Answer 1

Have you added the dll into your project references list? If not right click on the project "References" folder and selecet "Add Reference" then use browse to locate your science.dll, select it and click ok.

edit

I can't see the image of your VS instance that some people are referring to and I note that you now say that it works in Net4.0 and VS2010.

VS2008 projects support NET 3.5 by default. I expect that is the problem as your DLL may be NET 4.0 compliant but not NET 3.5.