I have a 3 year old son who somehow refuses to be potty trained. I've tried so many ways into getting him to go either on his little toilet or the big one, we bought him the little seat to put on the big toilet thinking that will help but it didn't. I tell him I'll reward him if he goes on either one, he still wearing diapers even training pants. I want to put him in pre-school next year but at this stage I don't know if he'll learn by next fall hoping he will. What can I do?