I can't take a picture in RAW because the last script I used is still working and I don't how to stop it !
I think I understand now.
When you are in
<ALT> mode, pressing the shutter button does not take a picture - it starts the currently loaded script. If you want to take a picture, simply exit
<ALT> mode and then press the shutter button. If you have RAW enabled, CHDK will save a RAW image for you even though you are not in
<ALT> mode.
The same things works when you use exposure overrides. You have to set them up with the CHDK menus in
<ALT> mode, but they are active when you are not in
<ALT> mode and doing normal shooting.