What kind of kibble are you feeding? Like Jenny said, stuff is coming out the other end undigested/under-digested - so it still smells like food to your kiddo. You may want to switch to a higher quality kibble if you're not already.
What I'd immediately recommend is that you buy
Solid Gold's S.E.P. (Stop Eating Poop) - we had to use that for Wylie as a pup and it stopped the habit immediately after we started using it.