Can some one help me with my platy breeding Thanks

I have 4 platies: 1 Male redwagtail, 2 Female moon platies, and 1 Female tuxedo platy. I want to know how to get them to breed. The water temperature is usually about 78-80 degrees. The Ph is around 7. No one is sick. They live with an albino corydoras and a dragon goby. I am sure the wagtail is male and the other fish are females. No one is pregnant and everyone is healthy. I usually feed them flake food, but ocassionally some brine shrimp. Can anyone help me. The pet stores don't know anything about it and can't help me. Can anyone out there help me. THANKS A BUNCH!

Well the platies take their time to breed. If they are in a newer tank it may take a longer time. But you might try to add a dominate male in the tank and a few more females because the more females the more of a chance you have. Also try and lower the temp about 2 degrees, that might help. Just give them time and they will start to breed like crazy. Ive had them for 6 years now and mine breed about once a month so i am wel knowledged in this area. Hope that helped you