How do you get a tot to poo?

really quite disgusting i know but hey.my daughter has taken to the potty quite fantastically but has been for 2 poos in 2 weeks!its starting to become an issue.she is clearly in pain but refuses to go because she says it smells (i told her that everyones does thats life!). I have exhausted every method i can think of to get her to do it (even bribery!)and i just dont know what to do! I could get a dog to do this more easily than her!