Training to the coop.

I have a flock of 8 bantam chicks that are 10 weeks old. They are a mix of different silkies and Cochins. Every morning I let them out of the coop into the large run they love in but every night they just go to the front corner of the run to sleep. They huddle up out in the open and just lay there. I have to pick them all up and put them in the coop every night. But the funny part is they go in and out of the coop all day but won't go in at night. Any tips to try? My large fowl never had a problem putting them selves up at night.