This short error message is usually caused by a linker error. Go through the compilation & linking report on the output window and check for any messages.
Thanks for answering, I have download it, and I get the same error when trying to build :(
got it working ones, but it was a bit of a pain ;-)
Can you provide archive of your project that we can have a closer look?
Please also let us know which creator version you are using.
All the Best
In the end I could built it, ;) I didn't realized that I should include two different paths for includes...