My hens have been in the coop since they were about 6 weeks old. They had a heat lamp on until recently. They are now full grown and it has been fairly warm here so I unplugged it. When the light was on they all went inside at night and roosted. Now three of my hens go into the coop at night but they sleep cuddled up in the corner on the floor. My one hen refuses to go into the coop at night and puts up a fight when I put her into the coop. What should I do?