On those checkin machines my passport doesn't work either (maybe I don't do it right?) so I type the booking number or use my frequent flyer card or credit card anyway. As long as it scans properly in immigration controls I don't care.
My strangest experience with self service kiosks was in SVO. I checked in and selected a seat and it said boarding pass had been printed out, but I looked everywhere on the machine and no boarding pass. The machine had probably ran out of paper. Tried another machine and I got an error messag, so I went to a counter and got my boarding pass there.