With my oldest it took 6 months longer for that. What I did was when he pooped into his diaper we walked it to the potty and plopped the poop into the toilet waved and said bye bye poop. Kids tend to have a separation issue with it, so I showed him that is where it goes even when we do not sit ont he pot. Then after a little bit of time I bought a toy that he did not have but liked(thomas the train trains) and put it up in the bathroom where he can see it and told him if he poops on the potty he would get it. It worked. He had a few ooops but the way I fixed that was taking away the last prize after he oopsed 2 x's in a row, if he kept oopsing I would take them all away. He would get them all back after he went on the potty again. Mind you this punishment thing was only after I knew he got the hang of it and was playing with me (testing to see what would happen if he started pooping in his pants.).