Chicks Hit The Town

Once they reached 8 weeks and all of their feathers had come in it was time for them to get a place of their own. The stagecoach chicken tractor that I had built when I first got the chicks was ready for move in day. The first couple of days we left them outside in the stagecoach for a few hours during the day. Once they seemed ready we left them in over night. Everything went off without a hitch. Only problem is they would not sleep in the coop. The next question; How do I get chicks to sleep in their own room?