Babysitting Tips?

I've newly started babysitting.. I'm almost 16 and I've babysat for this family a few times now.. they know me through a family member and the kids love me! They always draw pictures saying they love me and I'm the best babysitter ever... but I do have one problem. I always babysit in the evening and obviously thats bedtime. The kids are 3 and 6. The 6 year old usually goes to bed fine for me but the little girl never stops.. she will be in her bed, but awake and talking, and I'm honestly sitting up there with her until 11 when her parents get home. I've tried everything, tiring games, pretending to fall asleep, stories, bribery and nothing works. And the mom doesn't even get mad with her cause shes just glad that her kids aren't crying cause they usually are with babysitters. I want to know how to get this kid to sleep... help me!