[ALUG] HP Photosmart R507 not being assigned usb device number

Hullo there, I'm trying to use gphoto2 on a debian linux box. The camera in question is an HP Photosmart R507, which is detected when usb is plugged, but no device is being assigned in /proc/bus/usb. Any ideas as to why welcome. It works on another debian box okay, and I can see the new device appearing. Thanks, Jenny