I've been working on training my year old chihuahua/beagle mix and it seems like she has trouble focusing on the training. I'm using treats, in a quiet environment (my living room) with very few distractions. We are working on "look" and "sit" (not at the same time) she will sometimes do the behavior and other times she will just walk away from me. Should she be on a leash? are my treats not good enough (she seems very interested in them, smelling, wagging tail, etc.)? Or do I just have a stubborn dog? Any advice?