Does Altera's FFT Core support backpressure?

Hi, all.

I'm using FFT Core (Variable streaming, 256 points). I want to control datastream via signal "source_ready", but FFT stall after 2 frames.

From fft_ug:

"source_ready ... Asserted by the downstream module if it is able to

accept data." What I doing wrong?

Here SignalTap snapshot (_http_://img834.imageshack.us/img834/4803/fftstap.png)