hello all, my 3.5 year old is potty trained for weeing but he refuses to poo on the potty. This has been going on for ages and i am fed up of washing dirty pants. He isn't scared to go on the potty to poo and i know he can as he has done it successfully once or twice. He thinks its hilarious that he does it in his pants and clearly does it on purpose. Reward charts and treats not worked. Any advice ladies?