chickens not using ther perches

I have moved my chickens into a large barn beacuse we have a pesky fox about but they do not seem to be using the perches provided any tips?

When I got my new girls I had to pick them out from about 50 in a barn. There were perches provided but most of them were sleeping on the floor.
I suppose it depends on how you feel. Although they are birds and should roost they do what's most comfortable.
I spent months and months moving mine at night then gave up. It wasn't that much hassle to poo pick the nest box each morning.
When I got more girls they all went and roosted on the bars together!!
Flock mentality and not enough room for all in the nest box!!!