My hens wont sleep on a perch

Hi there im looking for help i have bought 3 isa brown hens they are now 21 weeks old i havent had an egg out them yet and also they always want to sleep in the nest box
Thanks

Maybe you should show them how it's done?

Actually being a bit serious there, I had chickens years ago and when they were new wee baby chooks they weren't used to perching and we had to put them on the perch to show them how it was done and fed them some grain, stroked their feathers so they got used to the idea. Once the food was gone so were they bit it helped.

I miss having chickens, I'm pining.