Thanks for your reply, but - no, Im not changing any settings.
I am outside taking one picture in daylight then I walk inside to a dark room and take another picture (flash off)
When I check the filebrowser the 'inside picture' produced a raw (.crw) file and a jpeg but the 'outside picture' produced only a jpeg.
I do not change any settings between the 2 pictures and I have tried it many times with different builds.
I know it sounds strange - but this is what happens.
(I have also checked the memory-card on a computer as well as the filebrowser on the camera)