New Post: Unable to find the type or the namespace of Ghostscript

I don't know how to solve this problem.
I need to use Ghostscript.NET, so I downloaded Ghostscritp.NET.dll and put it in my folder project. So I added the reference do the dll.
But when I try to do "using Ghostscript.NET;" in my classes it gives me an error:

Unable to find the type or the namespace of Ghostscript

and doesn't let me compile the project. How can I solve this problem? I realy don't understand what I'm doing wrong.