Hi,

I've changed the code so:

1) Include the sentence using namespace Qwt3D; in both MainWindow.h and MainWindow.cpp files, so I can use directly SurfacePlot instead of Qwt3D::SurfacePlot.

2) I've added the library LIBS += qwtplot3dd.dll (of course I've also copied it to the executable folder)

3) Now I get another type of error. "Microsodt Visual C++ Runtime Library" "This application has requested the Runtime to terminate in an unusual way. Please contact the application's support team."

Any ideas?

Thanks!!!!!