My chicks did the same thing when I moved them into their coop. They would all pile up in a bundle in the floor, I tried to put them in the roosting box many nights like you did and the following night they would be in a pile again so I let them be. When they got older they moved into the roosting box by themselves. Two weeks ago, I moved my new set of 6 week old chicks in the coop. I have a partition in it that allows the chicks to see the pullets but they cannot mix. I believe the chicks learned by watching the pullets roost in the boxes because from day one, they have roosted in the box, I just helped them by putting a shorter roost next to the box so they can jump into it. Just let your chicks pile up at night, one of these days they will surprise you when you see them roosting in their perch.
