That vaguely smells like a permission issue. If you have libmtp installed, check what mtp-detect says as your usual user, then as root.
If it works properly as root but not as an user, fix your permissions to be able to 'talk' to USB devices/your specific USB device as your user (udev rule?).
I'm hoping every recent distro out there has a mostly sane default setup, with a dedicated group for this kind of thing, so you might also want to check your distro's doc on that front, it might just be a case of your user not belonging to the right group.
Last edited by NiLuJe; 10-13-2012 at 05:52 PM.