Lifetime movie, i think?

All I remember is that these two girls (sisters) I think go home late at night and the one is told to shut the gate for the wooden fence and she shuts it but it doesn't lock then one goes to there tree house and the other goes inside the house and the next morning the one sister who went in the house wakes up and so do the parents and go the tree house and I think the girl in the treehouse is dead, I'm almost positive that she's dead but I can't remember for sure. Do have any idea what I'm talking about and that's all I remember?