[Erik Thered]

Hi, I am an FCP editor and I just had exactly this problem when bringing some DVCPRO HD footage into AE CS4. We shot direct to FCP studio 2 via firewire from a P2 camera. The QT’s had audio, but when we took it into AE, there was no audio, no waveform – nothing! After talking to everyone and her dog, and getting absolutely nowhere, I noticed that the QT files had two mono tracks of audio, one with audio, and one without. I deleted the empty audio track in QT Pro, and voila! when I took the file into AE, the audio was fine.
I hope this works for you.

Erik.