sane recognizes the scanner of Lexmark X1150, but it does not work

<code>
$ sane-find-scanner

  # sane-find-scanner will now attempt to detect your scanner. If the
  # result is different from what you expected, first make sure your
  # scanner is powered up and properly connected to your computer.

  # No SCSI scanners found. If you expected something different, make sure that
  # you have loaded a kernel SCSI driver for your SCSI adapter.

found USB scanner (vendor=0x043d, product=0x007c, chip=rts8858c) at libusb:007:003
  # Your USB scanner was (probably) detected. It may or may not be supported by
  # SANE. Try scanimage -L and read the backend's manpage.

  # Not checking for parallel port scanners.

  # Most Scanners connected to the parallel port or other proprietary ports
  # can't be detected by this program.

  # You may want to run this program as root to find all devices. Once you
  # found the scanner devices, be sure to adjust access permissions as
  # necessary.
</code>

<code>
$ scanimage -L

No scanners were identified. If you were expecting something different,
check that the scanner is plugged in, turned on and detected by the
sane-find-scanner tool (if appropriate). Please read the documentation
which came with this software (README, FAQ, manpages).
</code>

<code>
$ sudo scanimage -L
[sudo] password for luigi:

No scanners were identified. If you were expecting something different,
check that the scanner is plugged in, turned on and detected by the
sane-find-scanner tool (if appropriate). Please read the documentation
which came with this software (README, FAQ, manpages).
</code>

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: sane (not installed)
Uname: Linux 3.3.6-030306-generic-pae i686
ApportVersion: 2.0.1-0ubuntu7
Architecture: i386
Date: Tue May 15 20:27:54 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release i386 (20120423)
SourcePackage: sane-frontends
UpgradeStatus: No upgrade log present (probably fresh install)