PowerShot G1 can't switch to RAW format

I'm trying to use my old Canon PowerShot G1 with gphoto 2.4.10 provided in ubuntu 11.04 .
The camera is detected fine and i can take shots in JPG format, but i can't switch to any imageformat with RAW, i always get this error:

# gphoto2 --set-config /main/settings/imageformat=0
Detected a 'Canon:PowerShot G1'.
Could not change image format

If i try to check shootingmode i get
# gphoto2 --get-config=/main/settings/shootingmode
Detected a 'Canon:PowerShot G1'.
Label: Shooting mode
Type: MENU
Current: Unknown
Choice: 0 AUTO
[...]

If i try to set it to number 4 (M) i don't get errors, but the settings remains in "Unknown" mode
# gphoto2 --set-config /main/settings/shootingmode=4
Detected a 'Canon:PowerShot G1'.
Shooting mode changed

# gphoto2 --get-config=/main/settings/shootingmode
Detected a 'Canon:PowerShot G1'.
Label: Shooting mode
Type: MENU
Current: Unknown
Choice: 0 AUTO
[...]

Something i'm missing or there are some problems with the G1?