xsane does not work

after new installation of version 7.04 my scanner Canon LIDE20 does not work.
xsane (0.991) is installed and can start.
a scan only give a black canvas.
I have deinstelled. installed, restard, and, and, and ....

ProblemType: Bug
Architecture: i386
Date: Sun May 13 18:12:33 2007
DistroRelease: Ubuntu 7.04
ExecutablePath: /usr/bin/gnome-panel
Package: gnome-panel 1:2.18.1-0ubuntu3.1
PackageArchitecture: i386
ProcCmdline: gnome-panel --sm-client-id default1
ProcCwd: /home/gladio
ProcEnviron:
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-panel
Uname: Linux lhj9 2.6.20-15-generic #2 SMP Sun Apr 15 07:36:31 UTC 2007 i686 GNU/Linux
UnreportableReason: Das Paket stammt nicht von Ubuntu.