exactly it's low limit omaha. Even though you had a lock on the hand you played it like you should have, that holdem player playing omaha with his overpair and i don't know what else :P backdoor flush possibilities? you did right just got unlucky, trap hold em players in strong omaha hands and if they miracle outdraw they miracle outdraw you.
the tourney i was playing over the weekend in pot limit omaha, the turn gave me an ace high flush but it the players went bet, raise, i re-raised them someone pushed over hte top of me and it was a paired board, well one other guy called and i folded so fast obviously someone had minimum a boat. the guy that re-re-raised over me had a boat adn the guy that called him after that had a queen high flush, people sure do love their holdem, oh and that guy stuck around to complain how unlucky he was that his flush ran into a full house :P he should play royal holdem so he has much better bad beat stories.
<----I hate tournaments and tournaments hate me, so I'm loading up on all the donkey luck I can for the next ones :-)