Pee PT'ed but not Poo PT'ed

IA2TXGirl

The day after Christmas I hunkered down with DD to start the 3 day PT method. I will say it was one of the most frustrating experiences of parenthood to date! That said, it didn't click until day 4 when she went to bed and stayed dry the entire night. She proceeded to have 3 days accident free with the exception of pooping which she held for a couple days then went in her underwear during naptime. Here we are over a week since we started this journey and although she is a champ at peeing in the potty and virtually no accidents, she refuses to poop on the potty. Any suggestions? I am at a loss since she is holding it in and only giving me one teaching opportunity every few days, and even then waiting until naptime so there is nothing I can do about it. I, of course, take her to the potty before nap, and if she is still awake in her room for a bit I will get her up and put her on the potty again before she falls asleep. When she does go in her underwear, I take her in the bathroom and put it in the toilet and tell her what it is, where it goes, and have her flush it. When I think it's time for her to poop instead of pee I will ask her if she needs to "go poo" instead of "go potty" to help her understand, but still nothing. She gets rewards (a piece of candy and the opportunity to play with a new special toy - her stamps) when she goes pee. And I would definitely give her a reward for going poo, but I just don't think she understands the difference.  Any thoughts would be greatly appreciated. TIA!