Potty training woes....

Is it really THIS hard to go potty? She's PERFECT at the sitter.....doesn't even wet during nap time.....unfortunately, she WILL NOT poop on the potty. Not scared, just won't. Will NOT tell you when she has to go (just right afterwards)! Doesn't matter if she's in panties or diapers....poops.....do you know how GROSS this is???? I do and it is something I can very well do without in my life!!!!

I bought stamps and she gets one stamp for pee, two for poop.....we only earn one at a time. She'll tell you how many she can earn, just won't do it.

Cookies at the sitter if she poops on the potty....no cookies and is mad at sitter, "going to tell my mommy" b/c sitter won't give her any cookies!!! OMG, REALLY???

Any, any, any words of advice would help and be appreciated. I'm all about bribing, but just don't know what the motivator will be. We were at a neighbor's house playing yesterday and she pooped in her panties....swooped her out the door, went home, bathed and straight to bed. Oh, my, how unhappy she was....but it won't fix the problem.

Please help!