S. - my son (now 10) did that at first too. It was like clockwork, we'd put on the nighttime pull up, wait for us to leave, go sit in the corner, squat and go. I actually spied on him a couple of nights to catch the routine. Then, the next night I tried to catch him in the act and run him to the toilet. However, that wasn't always successful. But, it got him going in the right direction. Then, about a month later, we were on a long distance trip and had him in a pull up. He said he need to go poopy. We weren't near an exit with a toilet, so we just told him to go in his pull up if he needed to. He cried and cried and refused to do it. So, we finally found one and he went on the toilet. It's like it finally clicked. So, have faith. And, remember, some kids see pooping as losing a body part - a bit tramatic. So, when he does go in the toilet, allow him to wave goodbye, etc. Set the example when you go too.