Have any of your chickens been hanging out on the ladder? You might want to put some kind of netting on if they haven't. At 4 1/2 weeks the rungs are too big to be comfortable for my girls, although I'm not sure if that would be the case at 6 weeks.
It's torture, though, to watch them all happily hopping on and off the ladder, occasionally getting curious and peering into the coop, but never quite actually going in. Hurry up, birds!
my 6 week olds are still sleeping outside huddled on the ground. The 8 week olds seem to get it and are in the coop at night.. Give them time I am told.. as long as the are sleeping and not squawking all night, they should be fine.
I put my chicks in the big coop at 5 weeks. I have 14 LF Cochin, and thank goodness they are a friendly, docile breed. I had to put all 14 of them in the coop every night for 2.5 weeks. If they didn't come running to me every time they see me it would have been a real chore. Just this past week they made it in all by themselves, and as of a couple days ago no one is sleeping on the floor. Give them time, it takes some longer than others and you'll be so proud of them when they become big kids and go to sleep all by themselves. Good luck!