Hello, I have a 9 year old yorkie, who always has had issues when it comes to house training, however, he does pretty well. He will have an accident, which is usually urine. He has no issues pooping and peeing outside in the morning when I leave him out. He has been recently going ot my boyfriend's with me and he will not poop in his yard, then when we come home, we come home having to clean up poop. I'm not really sure why he won't go in his yard, he has gone a few times, but he has stopped now. Any suggestions or reasons as to why this is happening?