I am a brand new chicken farmer. Started w/ 2 RIR and 1 Leghorn now 17 weeks. They learned to walk the plank to their coop at night just fine. I added 7 more assorted chicks now 10 weeks old. I had the older and younger birds separated until they were all about the same physical size. I would hand carry the younger ones in and out each day. They could all see each other as there was just wire fencing to separate them (in coop and in the run). Now that the fencing is down, they get along just fine. The older birds still go in to roost on their own, but the younger ones don't do so reliably. Some walk the plank and then just stop in the doorway and block the way for the rest. The door is on center with slanted ladder type roosts on either side and they don't seem to use the roosts. I have an electronic door closer and don't want anyone to get caught (though it moves so slowly that's probably not a big risk). Any suggestions on how to get everyone to move in at night?