Bear, who was given to me as a "housetrained dog," is not. He knows to pee outside, but he always poops inside. Even if I walk him on a leash, or let him out in the backyard for 45 minutes, he comes right in an poops on the rug. He goes out 4-5 times a day too. This is extremely frustrating! Any idea on how to teach him to poop outside ONLY? Thanks!