Brightness controll keys don't work in Toshiba T135

It only works if i do this from a terminal:
sudo setpci -s 00:02.0 F4.B=<insert_value>

where <insert_value> is a number for screen brightness (0/99).

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: gnome-power-manager 2.32.0-2ubuntu2
ProcVersionSignature: Ubuntu 2.6.38-10.46-generic 2.6.38.7
Uname: Linux 2.6.38-10-generic i686
Architecture: i386
Date: Sat Jul 9 12:54:43 2011
GnomeSessionIdleInhibited: No
GnomeSessionInhibitors: None
GnomeSessionSuspendInhibited: No
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha i386 (20101126)
MachineType: TOSHIBA Satellite T135
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-10-generic root=UUID=3622343a-e044-49d5-a9df-0448206a54d1 ro quiet splash pcie_aspm=force vt.handoff=7
SourcePackage: gnome-power-manager
UpgradeStatus: Upgraded to natty on 2011-04-21 (78 days ago)
dmi.bios.date: 07/08/2010
dmi.bios.vendor: TOSHIBA
dmi.bios.version: V2.70
dmi.board.name: Satellite T135
dmi.board.vendor: TOSHIBA
dmi.board.version: Not Applicable
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: TOSHIBA
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnTOSHIBA:bvrV2.70:bd07/08/2010:svnTOSHIBA:pnSatelliteT135:pvrPST3AU-00J008:rvnTOSHIBA:rnSatelliteT135:rvrNotApplicable:cvnTOSHIBA:ct10:cvrN/A:
dmi.product.name: Satellite T135
dmi.product.version: PST3AU-00J008
dmi.sys.vendor: TOSHIBA