Quote Originally Posted by mickey
Is it #include "mainform.h" the problems?
Probably yes.

I need take it here...
No you don't. Do you use methods defined there?
But wich is different between include in implem and in declaration? I thought it was the same for success of compile...
No. You should avoid including to much files in headers, because it slows down the compilation. But the reason of failure might be that qmake sees that it needs that included file in the current file, but that file is included in the other one, so it depends on it and thus it creates a cycle. Of course it might be something different, but you should try removing that include from the header file.