P.D.
I had the same problem with my son...he had no problem going potty in the toilet, but he would poop in his pants. I actually caught him right before he went one night (he gave the shiver) and I ran him in and put him on the toilet and ever since then he never had a problem going poop on the potty. Once you get her to do it once, she probably won't have any more issues. Good luck - I know how frustrating it can be:)