D.B.
It sounds like she is nervous about it. Try reading to her or allowing her to look at a book while she's on the potty. Do you have a portable DVD player? Maybe should could watch that or something else so that she's not thinking about it. I think she'll feel more comfortable with pooping once she has more experiences with it. If she doesn't like the "kerplunk," trying playing some music in there. Does she seem to be constipated? Maybe it's uncomfortable for her or painful and she doesn't want to go. What about adjusting her diet so that her bowel movements are easier for her. Try adding more apples, apple sauce or apple juice. An apple a day with help with that. She won't be able to avoid going to the bathroom. Good luck!