Rocketfish web camera problem

I have iChat 4.0.5 on an older PowerMac G4 (USB 1.1) and just got a Rocketfish web camera model RF-WEB2C. On my PowerMac it indicates that the camera is in use by another application. When I plug it on a newer MacBook Pro it works fine. Is the problem the USB? Any solutions? Are there web cameras that work on the PowerMac G4?
Thanks