In response to your question... what we did, we kept the chicks in a very large box (incidentally the box our fridge came in when we bought it!
) indoors until they'd grown a fair few feathers and wouldn't get cold outdoors at night. Then, we moved the fridge box into the coop and placed them in it every night: that way they could see that the coop was like home in a way, just outside. Then slowly they began to climb into the box by themselves, and soon got into a habit of perching on the edge like they were roosting instead of going all the way in. When we took the box away, they adapted easily to the roosts.
Especially to ChooksChick! I suspected it had something to do with light! I will place a small lantern light in there at dusk tonight and see what happens!! I will post some pics soon!! Thanks again BYC!!!