Strange, Isn't It?

K Q
K J 9 8
K Q 9 8
A 3 2
10 7 4 2
Q 7 3 A 10 6 5 2
6 5 3 2 A J 10 4
K 7 5 4 Q 6
A J 9 8 6 5 3
4
7 Contract: 4, 6 spades
J 10 9 8 Opening lead: hrt 3, dia 5

WestNorth East South
Pass 1 Pass 4
Pass 6 All pass
WestNorthEast South
Pass 1 1 3
Pass 4 All pass

It always strikes me as strange that declarers who get a favorable opening lead, a gift even, wind up going down on a fairly safe contract. But such is often the case. One declarer had no chance when his partner shot the level of the contract to 6. No Blackwood, even? To be sure, Blackwood wouldn't have spared N-S from a negative score, but presumably wouldn't held the damage to minus one -- tying the other declarer in 4 who misplayed the hand.
There's not much to say about the play of the declarer in slam. Opening lead was the 5 of diamonds, East winning and cashing the A of hearts! If that's not enough to assure declarer of 10 tricks (declarer could have sluffed clubs on the Q of diamonds and K of hearts, eschewing the double finesse in clubs), East now led a low club from Q 6 (!) It would take an idiot to lose more than 3 tricks on that defense. But given the slam bid, declarer was down 2.
The second declarer had jumped only to three spades allowing his partner to settle in a safe and sane four. Opening lead was a heart, declarer going up with the K, East winning and returning a heart, which declarer ruffed. Now declarer led a diamond to the K, which held and . . . . which held! Hey, man, that's a gift! You now have an overtrick coming if the double hook in clubs works, and if it doesn't, you'll be making 4 while others are going down! So how did a declarer, with an overtrick offered go down? Well, lemme see.
Declarer now ruffed a heart and started his double hook in clubs, pushing the 8 through to the Q, and ruffed a heart return with the 7 -- and was overruffed with West's 8! With 9 trump, including the top 4 cards, and three rounds of hearts, including one by declarer, he had to hit clubs -- and ruff with his lowest trump on the fourth round of hearts? It makes no sense.
Still, East had given declarer a trick by not taking the K of diamonds, so declarer has only thrown away the overtrick offered, and still should've made, no? Now a diamond from West was ruffed and declarer -- still not wanting to draw trump with the top 4 and only three out now -- chickened out of the second half of the double hook, went up on a club lead. And that's how he went down when the opponents said, "Hey, dude, ya want an overtrick?"