[ltp] Brightness keys on X61 Tablet

[character]

Hello,

here's my problem:
The brightness keys on my X61 Tablet don't work.

I'm running Debian sid, kernel 2.6.23.1 patched with the latest
thinkpad-acpi release (v0.18-20071013). When I press Fn-End (brightness
down) acpid catches two events, 
1) "ibm/hotkey HKEY 00000080 00001011" and 
2) "video LCD0 00000087 00000000".

The first executes /etc/acpi/thinkpad-brightness-down.sh which doesn't
do anything because it's a Lenovo laptop. The second event
executes /etc/acpi/video_brightnessdown.sh which itself executes
acpi_fakekey 224. I assume now something should happen, but it doesn't.

It doesn't matter if gnome-power-manager is running. If it runs,
however, a small 'popup' with a brightness-symbol and a bar shows up.
The bar is empty and won't change.

I can change the brightness level by echoing '5' to /proc/acpi/ibm/cmos.
However, changing /etc/acpi/thinkpad-brightness-down.sh to do this (echo
5 ...) does not help. That is, it doesn't work if the video-ACPI-event
is triggered and X running. It does work if X is not running, though.


Thanks in advance,

char