Need some potty training help-poop only...

We have been potty training with Sabrina and the past few months she has been GREAT with going on the potty. She tells us. She can hold it if we need to walk a bit or if we are in a car.

But poop is horrendous. She knows where it should go. She has made it in there. We give her lots of praise when she does it in the pot. But most of the time she makes in her pants.

I try to catch her when she looks like she is squatting and she gets nasty and screams and pushes me away.

Any advice?