Pooping is haaard

This is how she gets her M&Ms.  She'll poop in her diaper and ask for M&Ms (or jelly beans or whatever).  I tell her no, she has to poop in the potty to get an M&M.  So she goes and sits on the potty with the poop still in her diaper and says she did it.  Sometimes I give in because I figure at least she sat on the potty.  Who's training who here?