Can you share pictures of your coop? Many of the kits and prefabs lack ventilation and don't have room for the number of chickens they claim it will hold. They may not want to go in because it's too stuffy or crowded.
You have been given great advice on the mites, along with bugs, agression from the others will definitely keep them from using the coop. Mite and bug treatment, along with physically putting them in at night to train them is probably the best way to go.
Welcome to BYC!
To check for mites, run a paper towel over/under the roost at night. Blood on the paper towel means mites.
Can you post the following:
Picture of coop interior
Coops size in feet/inches and also roost length in feet/inches
How many chickens are in the flock?
We're they all raised together? Are the easter Eggers new or younger?