I think the OP is saying they will roost in the coop, but will not perch on the ladder perch/roost that is in the run.
My girls love to lay in the dirt, perch on the stairs, stand on their perch and will sometimes even perch on the perch.
My girls love to lay in the dirt, perch on the stairs, stand on their perch and will sometimes even perch on the perch.