S.C.
I have a 3 year old daughter that just got potty trained. Sometimes you have to bribe them or wait for when they are ready. Make it known to him that if he sits on the potty and pees and poops, then he is a big boy. Tell him that if he uses it he will get a reward afterwards. He will use it eventually. I tried potty training my daughter ever since she turned 2 but she was never ready until now. She is fully potty trained now. Just keep on working with him on it and when he is ready he will do it.