I have a 3 year old. He is not trained. He will sit on the toilet no trouble, but I really don't think he gets the concept yet. He will tell me after he's pee'd in his diaper. If he's sitting on the toilet and I walk away for a moment and come back and ask if he's pee'd he always says yes... but he hasn't. If I ask him if he's pee'd in his diaper he'll say no even if he has. He's just not making the connection... any suggestions?