I try to setup 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 althought i didn't setup one? So i'mnot able to confirm the dialog and add my printer, what's the reason?