leaving the court

[benbret]

We had this tonight in a girls varsity game. Team A has a throw in at halfcourt. 8 seconds left in first half. Team B sends in a sub and a team B player leaves the game. I am the lead and out of bounds. After the throw in, Team B #52 is in the low post and for some reason she thinks that the sub came in for her. She goes behind me and continues out of bounds and goes to her bench. We are playing with four B players. When she went behind me and went to her bench I stopped play for her leaving the court. After we talked about it the Referee said it was simply a violation and there is no penalty. Can a defensive player just leave the court without penalty? Rule or case book please.