Puppies, like children, unfortunately weren't born with the knowledge of how to sit/stay/come etc. Until we teach tell them what we want from them they wont understand. Its not something that will happen overnight or over a few weeks, it takes time and perceverence (sp). Dont give up, just keep at it and remember EVER SINGLE TIME she comes when you call, praise her constantly and reward her with a treat. One thing to keep in mind, if she has done something wrong and you call her to you and she comes you MUST praise her because she came when you called.
Good Luck!!
Trina