+4  A: 

You need to actually reference the library from your C# project. Right-click the project and then select "Add Reference". On the "Projects" tab, select the project and click "OK".

Dean Harding  2010-06-04 03:39:59
As its a DLL (Class Library), "Add reference" then click on the "Browse" tab and locate the DLL.
Jason Jong  2010-06-04 03:41:50
@Jason: That also works, except if he has the project in the same solution, then adding a project reference makes sure Visual Studio always builds them in the correct order (though you could also do that with an explicit dependency, but lets not get too complicated ;)
Dean Harding  2010-06-04 03:44:54

related questions

How do I change the blue borders in VS 2010?
.net framework 4.0 documentation
Is it possible to create ASP.NET MVC applications in VS 2010 B1?
Will installing Visual Studio 2010 side by side with VS2008 cause problems?
visual studio 2010 CTP expiration work around
Will the deprecated /clr:oldSyntax supported in VS2005 and VS2008 still work with VS2010?
Does Visual Studio 2010 have backward compatibility with visual studio 2008's addins ?
Summary of VS2010 feature list?
What features are people looking forward to in .Net 4.0 - 4.1
VS2010 vs VS2008 SP1 on Windows 7
Is there any T4 Editor for Visual Studio 2010 CTP2?
How do you use selected vertical blocks in Visual Studio 2008 and 2010?
Register DLL in GAC without Assembly Manifest
Why can I not edit a method that contains an anonymous method in the debugger?
Visual Studio 2010 - WPF / Silverlight and built-in Grid
Is Visual Studio 2010 CTP stable for everyday use?
.NET 4.0 and Visual Studio release date
Visual Studio Upgrade Advice 2008 / 2010
What is Visual Studio 2010 going to look like?
Visual studio 2010 Wishlist
Summary of new features in WCF 2.0?
Can I implement method_missing in C# 4 and have it actually return a value?
What new tools can be found in Visual Studio 2010?
Your experiences with Visual Studio 2010 CTP?
What features would you most like to see in Visual Studio 2010?