fblevel not working on powerbook 12" 1ghz (GeForce FX Go5200)

[Maximilian Gerlach]

Hi everyone,
fblevel - and so the brighter/darker keys on my powerbook are not
working :/
fblevel gives me the following result:

root at grammaton:~ # fblevel 3
ioctl PMU_IOC_SET_BACKLIGHT: No such device
root at grammaton:~ #

Any idea?

Thanks,
Maxi