Posted 2006-June-05, 07:47
Couple of issues.
First, with four keycards, 5♦ would be forcing on your partner and asking for trump queen.
Second, did you consider bidding 4♥ over 4♦ as RKCB (call it kickback or whatever, responder can not have hearts on this auction.
Third, you need to know about third round control in both diamonds AND Clubs, not just one suit. When Responder shows two suits (as you did here) opposite a balanced hand (as here), you need to use six keycard blackwood. Let's reverse the King and Ace of clubs to illustrate the point. Now opener still shows 4 keycards (the club king will count as one). Now you can ask about queens, find out about the diamond one, then ask in clubs, the doubleton will be all that opener needs.
I do all this starting with 4♥, so the bidding would be:
2C-2D
2N-3S
4D-4H* 4H = RKCB
4S-4N 4S=1 or 4, must be 4, 4N = queens?
5H-6C 5H = higher queen (diamond)
6H-7C 6C = looking for Kx of clubs
Pass 6H=any bid other than 6D shows it
Alternatively, in you method, bid 5♦ over 4♣, partner will show the ♦Q and the heart king. Now 6♣ should be a specific asking bid, and Kx is more than enough to bid the grand.
As for your question, 5♦ is absolutely forcing on this auction when opener holds four key cards.
--Ben--