My pup is 18 weeks old tomorrow and he refuses to come when called. He won't even acknowledge his name when called if he's doing something he's interested in (rolling in dead frog, roaming tall brush/grass, running to the creek). These things are all things he's not suppose to do. Actually, for the most part, when he's outside he doesn't think he has to listen. Inside though, he's the best dog. I'm just getting real tired of playing a game of chase every time I take him out to potty. Any tips? Please help.