richard wrote:sometimes I see them dancing but no result yet
That's the tell-tale sign. It may take a month or more, still, but it's going to happen. It's all in the water quality and the food. You must keep your water at optimal conditions and feed them well. It is very important that the female receive good nutrition to sustain her needs plus whatever it takes for her to produce eggs. Likewise, although it doesn't seem likely, the male needs equally good food or he will not be able to milt them properly. How old/big are they?
I don't do things according to "the book," but I get about 200 eggs every 2 weeks for the last 6 months from a pair that has only started spawning since January. I feed them a variety of flakes and pellets in the morning (make sure there's a good amount of Spirulina in there), dried krill in the afternoon, and something frozen in the evening. That can be mysids, raw shrimp that I would eat, scallops, flounder, beef heart, cyclops (whatever the corals don't eat), squid, etc. I try to give them a varied diet. I dose SeaChem's Reef Plus at half the directions, and I sometimes soak the frozen food with a little bit before feeding. Works for me. Also, I keep the SG a little lower than normal - about 1.022.
Good luck!