A Missed Chance

K Q 9 8
K Q 2
6 5
A J 6 3
A 7 3 2 J 10 6 4
8 6 A 10 7 5 4 3
J 7 K Q
Q 10 9 8 7 5
5
J 9
A 10 9 8 4 3 2
K 4 2

SouthWestNorthEast
1 1
2 Pass 2 NT Pass
4 Pass 5 All pass

This is a pretty egregious example of wasting a 3 no opportunity on minor suit game. I call it egregious because South doesn't even have a particularly good diamond suit. With any 3-1 split, the defense could hardly help but pick up 3 tricks, however inept it might be. Well, he didn't get that, but he was obviously subject to the loss of two aces and a trump trick, where 3 no couldn't be touched, in no small part because of the 2-2 diamond split, which this declarer needed to go down one!
It looks to me as though the defense would pick up the same 3 tricks in either no trump or diamonds: Two aces and a diamond. Which works a lot better in 3 no than in 5 diamonds. So a long minor suit should not prejudice you against no trump. If you've got the stoppers, if your partner says she likes no trump, you just may have the same winners in either contract, for a much better score in no trump.
In the play, the defense and declarer traded mistakes at a crucial point. West led a heart, his partner's suit: East can weigh two choices, one that her partner led a singleton, in which case she'd like to give him a ruff, the other that declarer is missing the ace of spades, which will be the setting trick, since East is assured of a trump winner. She chose to try for a ruff with a second round of hearts, but her partner followed suit.
Declarer won the heart return, took the ace of diamonds and continued with diamonds, the jack and king bumping. Now East shouldn't have had any ambiguity about a spade lead. If her partner has the ace, then obviously she'd want to lead it for the setting trick. If not, then declarer has enough side-suit winners for his contract and you haven't lost for trying. Further, the fall of the J of diamonds should have warned East that her partner had no more trump. But East led hearts one more time, allowing declarer to sluff his spade loser!
But all was not lost! Well, all was not lost for the defense! The declarer who'd squandered a 3 no opportunity now squandered his chance to make his second-best contract on a simple finesse: He laid down the king of clubs, led a low club and went up with the ace! Tough luck. Such a simple finesse.