FFT Megafunction problem

I'm currently working on a university project, based on the implementation of FFT on a FPGA. Now I'm using Quartus II 64-bit version 10.1, Stratix III with 50MHz clock rate and the Core is not responding properly.

The FFT core with the following parameters :

- Variable streaming

- Floating point / Single precision

- Length : 128 point

- Nature order in / Nature order out

I can use simulator tool to get correct simulation value (both real and imaginary part). I also observed signals by SignalTap Logic Analyzer waveforms, the FFT input signal was correct, but the FFT always output denormal number or zero. I tried to lower the clock frequency to 25 MHz, used different input sequence, other Quartus II version(11.0), but it gave me back the same response. these tests makes me think the Core may have some problem.

Therefore, I would like to ask anyone was actual tested the variable streaming mode (floating point) on the FPGA successfully? If so, would you provide an example to me (I only found FFT+IFFT BFP example on the official website)?

Thank you.