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.
I have one more question for the
OP related to this post. You didn't manage to check-in online for the FRA-SIN leg, but did you check in for that leg at a counter/machine at BER?
My suspicion is that OP did not check himself or the luggage in for the second leg at BER. The SQ agent gave him the wrong information about the luggage. OP did not look for the luggage the next day, and the luggage was left at FRA.