I try to set up my printer under Ubuntu. So far it worked that I succeed to install the drivers. But Ubuntu says: No driver available for this model. This is the problem that Ubuntu doesn't recognize the right model, so I have to add and the choose the right driver manually. No problem I thought. But when I try to add a printer, I'm prompted to provide a root password although I didn't set up one? So i'm not able to confirm the dialog and add my printer, what's the reason?