#2 is always the challenge, you are not alone. You didn't mention if he is using a little training potty or the toilet with a training seat? When they are training, it's all new to them, and they have fears. Through my research I came across the advice of honing into their fear and reassuring that fear, explaining that it happens to everyone, even Mommy etc.. Because what they are feeling is very real and a big deal, even if we think it's silly.With my daughter, she was training on the toilet and went poop only once, then was too scared to want to go again. I was able to find out from her, that she was afraid of the water splashing. So I borrowed a Potty chair from a friend, and explained to her it had no water and wouldn't splash. That worked, but honestly for me cleaning out the potty chair was worse than changing a diaper, it made me gag! So I was determined to get her on the toilet. We did a lot of talking about the water splashing, and how it happens to everyone, but not all of the time etc.. I even got out a big pot of water and put it in the tub and let her throw a toy in it, so she could see how the water splashes up, she thought that was funny. Within 2 weeks, she no longer needed the potty chair. When she was on the toilet, she would ask me, "does the water splash on you too Mommy?" I would say "yes, sometimes" she always felt much better knowing it wasn't only her. So, try to find out what he is afraid of, it could be anything, does it hurt (is he constipated?) Is he afraid of the poop flushing away? When he knows that you understand his fear and you are there to help him, it will get much easier. Well, that's what worked for us :) Good luck!