I have bred all sorts of cichlids, including peacock bass (which are harder to breed than most cichlids) and I have found that once they start to show courtship behavior, I do 30% or so water changes for 3-4 days in a row and then on the 4th or 5th night I do another water change with slightly cooler water and it is almost every single time that the next morning there will have spawned. I don't know why it works, but I have heard theorys that it simulates the rainy season when the fish normally breed in the wild. Who knows but give it a shot and I bet that they spawn for you. Good Luck.