Most dogs will listen when they feel your the pack leader. Maybe you could read: Be The Pack Leader by Ceasar Millan you can find out more about that here: www.cesarmillaninc.com
Some breeds are known for their hard headedness, such as my sisters German Shepard! His trainer emphasizes on the importance of being persistent. Stop, sit, down and no mean just that 100% of the time and not just some of the time. If it's her social behavior then you have to remove her from the situation if she's not listening to a command. She will eventually learn you're boss. PERSISTENCE is the key. I hope this helps.
LOL..When you find out, let me know!! Lucy listens to no one..she got a bad spanking last night for growling at my son and biting my daughter.