A Straight Flush That Doesn't Pay Off

The usual players: Ozzy (my big bro), Bert (the inventor of the Bert Classic, the Bert Light, and the Bert Death Spiral), and Ivan (my web guru and a man who I can never get to fold). Missing in action was Jesse. No matter what, Jesse will show up for a game, even if it means showing up at eleven. You've got to respect that kind of dedication to the life of sin. A new player named Ruben came in and was taking all of our money. He left ahead, but not that far ahead. Earlier, when he was way up, he had joked that he had to leave early. I said, "Try to leave; see how far you get." It was a joke, mostly.

Idiot Move of the Night: We're playing Omaha, and I'm holding two diamonds. The flop gives me an open-ended straight flush draw. Even if I don't make the straight flush, I can make a flush to my nine of diamonds, which isn't that high, but that might hold up if I play it correctly. There's some low betting and, without a made hand, I just call it. Fourth street comes down, and I make my straight flush. Amen. Everybody checks it down, and now it's my play. I have the nuts (an unbeatable hand), so I could check and hope one of the guys makes a decent hand and he bets it up. Maybe somebody is even slow-playing a flush and is going to try to get paid off on fifth. Okay, the classic/smart play is to check it and try to represent that I'm on a draw. Fifth street comes and somebody bets, I come over the top, and I get paid off nicely. Of course, I get greedy, like a dumb bastard, and I make the max bet, two dollars, and everybody folds. No fifth street and no fifth street betting. 

Poker Problem: What the hell is wrong with me?