Make sure your feeding your fish with a high nutrient diet, or live foods. Black worms i have found to be the best food for fattening up your fish and getting them ready for breeding. I would also treat the tank with a fungus medication even if you don't have that problem. The eggs and larvae are very vulnerable to anything at this stage. Also, check to make sure the male and female aren't actually eating the larvae and eggs. It isn't uncommon for them to do this the first few times or if they are stressed. I hope this helps. Don't give up, it's one of the coolest things raising fry.