.sof is not genrated (urgent)

we can generate some files from this megawizard too..so can we be assured that there is no license issue..or IP buying thing required if some files are generated from the megawizard fft function?

and why is that when using a fft_wrapper.v file available on the internet we used in our system, .sof is not generated..but when we remove that from both Qsys and our main system's .qip file, .sof is generated..

We have tried the codes for a simple mux also, .sof is generated..Just dont know how to approach to this problem.

thanks a lot.