iMovie doesn't recognize Sony DCR-TRV120 (DV Tape)

Hi, I'm new to Mac and loving it already. We just got an Intel iMac with iMovie '08, v 7.1 (506). I have an older (~8 years) Sony Hi-8 Digital camcorder that uses a tape. I used to use this with my PC using a Firewire cable and it worked fine. According to the iMovie help, most tape camcorders with Firewire connections will work fine, but it simply doesn't recognize the camera.

I have tried starting iMovie first, then attaching the camera and powering it on to VTR mode (and vice versa). It never appears in the import list, only the iSight camera.

Any hints on what I might try? I searched the forums and didn't find anything quite like this. There are no other drives connected.

Thanks!