It works now.
By the way I'm using VC++ 2008, not Dev-Cpp now.

And after some testing I found out, that a dll written with VC++ doesn't open correct on some computers. I tested it on 4 different pc and only on one it' was opened. Did somebody already had this problem? What are typical mistakes when this problem occurs? Wrong headers/libraries, wrong project settings?

Dark_Samurai