Comment 36 for bug 145239

Just a wild guess: (had this troubles too)

using udev (but maybe with wrong rules?)

1. check if it works as root
 -> if yes continue
2. check you got write permissions on your camera
$ ls -l /dev/bus/usb/*/*
 -> have a look at the respective device...
You don't? -> set them manually and check if it works now...

Solution: you probably want to update your libgphoto package to a recent version
or correct the udev rules manually.

PS: Need more information: see
http://bugs.gentoo.org/show_bug.cgi?id=153471