We had to "re-train" our flock recently after we added new roosts to their coop, as well. It seems like they need to be placed on the roost for at least the first night or so, until they become confident about what is expected of them. After that, they appear to get the idea on their own, though. We also had to teach them to go inside each night, by carrying them in and locking the popdoor for a few days. Again, they learned what we wanted pretty quick. Now, we usually leave the popdoor open, since they can go in and out on their own. We moved some new chicks out to the coop about a week ago, and the first night, one of them didn't follow the rest inside when it go dark. We go out each night to round up any stragglers, but everyone seems to get the idea now that they were shown what to do. I've come to the conclusion that chickens need instructions for just about everything you expect them to figure out.
