Hi
Buy another peepee box put it by the the other one and see if that helps...dogs don't pee and poop in the same area...I have 2 babies and they are outside trained and when I let them out...they go to one side of the yard to pee and the other side of the yard to poop...so that might be why he is pooping by the box and not in it cause has already peed in there and doesn't wanna go back in where he as already pottied.