Error 12007 in Quartus with files from Megacore

Dear Members

I am working on harmonic detection with FFT.I am using FFT Megacore for that.This was generated using DSP builder Simulink. For simulation Matlab is used.Then i open Quartus.Files are added to the project. I am getting error: Error (12007): Top-level design entity "lab1" is undefined. I have no idea what is top level entity in Mega core. I have gone through other posts.But still issue is unresolved.Thanks for help.

Best Regards