Raising partner to slam on a void

I've decided that the joys of raising partner to slam on a void are over-rated.  At least week's regional in Cromwell, CT (the A/X pairs), I picked up the following hand: ♠ –  ♥ T32 ♦ AKQ985 ♣ AQJ7.

Partner opened 1♠ (11-15 hcp and five or more spades) and I responded 2♦ (game-forcing).  Partner bid 3♠ showing a solid suit.  I was angling for partner to declare either 6NT or 7NT.  So, I started with a cue-bid of 4♣.  Since I had made a 2/1 call in diamonds I hoped that with a heart control, he would be the one to bid 4NT (our key-card ask) and therefore be the notrump bidder in a slam.  Instead, he bid 4♥.  I didn't know whether that was a the K or the A (or conceivably a singleton?), so I now bid 4NT to find out.  He responded 5♠ showing "two with".  That meant his heart holding was at best Kx.  I was pretty sure he didn't have a heart void because he would have jumped to 5♥ (exclusion keycard ask). I therefore had to give up on a grand, and since I couldn't guarantee the ♥A was on my left, we would have to play in spades.  I therefore raised to 6♠ on my trump void.

Unfortunately, my good friend Bruce Downing was on lead and, as is his wont, he was listening to the auction.  He unerringly reached for a club (dummy's cuebid suit) and this was the layout:

Without a spade in my hand, there was no way to make the contract. There are a couple of ironies. First, the other eight scores were 980 (1), 490 (1), 480 (4), 450 (2). Those who didn't even try for slam generally scored 480 for 4.5 out of 8 because opening leader had no idea what to lead. One slam was successful and one pair got the next highest score by, presumably, protecting the HK from the lead in a notrump contract. Irony number two is that it wasn't hearts that was the problem. It was clubs! South (my hand) had to be the declarer (and since I couldn't declare spades), it was right as it turns out to bid 6NT myself. 990 would have garnered all of the matchpoints!