None of my 6 white rocks roost, 4 of them just lay on the shavings on the floor, 1 in a nest box and one under the nest box. I bought these hens as adults that were outdoor birds with no coop, could that be the reason why they don't roost...
Mine aren't roosting either. I have RIR, Buff Orp, Bl Aus, EE. The Buff Orp roosts a little, but the rest just hop up for a second to check it out. Mine prefer the bedding during the day and a shelf at night. I have a round roost about 2" in diameter and a 2" X 2" square roost.
Do you have other chickens? If so it could be the "just moving in and I have to be the bottom of the pecking order" that keeps them away. I know with my younger hens they would sleep under the roost floor for quite a while until they finally got brave enough to move up with the big girls.
None of my hens have ever roosted. It seems to have started with the BOs, then the bluebelle copied them, and now I have a black australorp and two orpington/cochin crosses and no-one has ever used the perch. It just got in the way so my husband took it out. They clearly prefer the nestboxes and floor, and I don't mind removing the poop every morning, so I don't have a problem with it!
If there is no rooster, they need to be shown how...
My hens did the same thing for almost a year after I got them, only half way through the winter when the rooster started to roost did they finaly get up there, and now only one hen is sitting on the shelf at night
goodluck, the floor can be dangerous at night if coop doors arent closed, please take precausions