fft core issue

Hi

I want to implement 1024 points FFT in cyclone II using dsp builder v6.0.

For this purpose I am tring to test the FFT core. But I can not solve this problem after 3 days effort yet.

when I try to take FFT of sine wave I got zero at the output.

Please guide me what I have missed in my model???I have attached fft_model.mdl file along this thread.

Please help me..