How big is your coop? How is it laid out inside? Can they sleep somewhere away from the adults?
After you put them in, what happens in the morning? Is your pop door locked so they are stuck in there with the adults or can they run out as soon as it gets light? Are they chicks getting beat up in there or are they co-existing peacefully. When I do this I find the chicks up on the roost and the adults on the coop floor when I open the pop door. The chicks have found a way to safely avoid the adults.
I do the same thing you've been doing, usually with about 20 chicks but this is in my grow-out coop, no adults present. After it gets dark enough for them to go to sleep I toss them in the coop and lock the door. One time every one went in on their own after only one night. A couple of times it took three weeks tossing them in every night for the last few to put themselves in. Typically a few start going in after two or three days and they are all going in after a week or so but each brood is different.
Before I try moving them into my main coop where the adults are sleeping I generally let them roam with the adults for a month. I have a lot of room so they form a sub-flock, avoiding the adults. When it is time to move them in I wait until dark and toss them in the coop. It's big enough they can find places to sleep away from the adults. I lock up the grow-out coop so they cannot get back there. Usually I only have to do this once but occasionally it takes another time or two for the last to get the message.
I don't see anything wrong with what you are doing but I wonder if your problem is what is going on inside that coop when they wake up the next morning.
