Originally Posted by lokijuh

Absolutely nothing to do with the missing luggage, but the earlier part of the OP's story has more or less confirmed my belief that if you have a connection involving different carriers on the same ticket, do not do web checkin with the first carrier, instead wait and do checkin at the airport (unless having done it successfully before). I am sure a check in agent at BER could pull a boarding pass for the SQ flight, but online, not so much.