My dog knows how to sit on command. When we are in the house she sits when I tell her to, but when we are outside she doesn't. I'll tell her to sit and she just stands there looking at me like a deer in headlights. Since she's a small miniature pinscher I've even tried crouching down and telling her to sit. I don't know if that's the correct thing to do but I feel like a giant towering over her. What should I be doing? How can I get her to listen to my command when we're outside?