Girls not using nesting box

Have you tried false eggs in the nest box's? We used some plastic eggs, then went onto golf balls. As pullets sometimes they missed but did not take too long for them to get the idea.

We also have some different sized boxes, some more 'private' than others and those larger ones where they lay in more seclusion seem to be popular with out girls. You could make some feed bag curtains that cover half the door maybe? Depends on your layout.

I have seen other peoples where they just make nest in the deep litter but that seems a bit messy for me.

 

A common mistake is the belief that just because a chicken is a bird that they should lay up high like they were a robin or something, therefor many of the nests provided for chickens are too high off the ground to suit chickens' fancy.

Chickens are ground nesting birds like turkeys, quail, and pheasants are so chickens prefer to nest on the ground but as long as the nest is lower than the roost and like the previous poster said "secluded" they should take to it like gangbusters. If we stop worrying about the comfort of our hens backsides or bending our backs to gather eggs, but instead use a slab of sod or turf the same size as the nest box and install it in the nest, grass side down then add a little straw to ease our conscience, I think your hens will take to laying in the nest.

Like with going broody some hens have had more or less of their natural instinct bred out. So this may or may not work for you but I predict that it will make a difference in most of the cases like your own.

Hens choose nest locations with an eye toward spending 21 days sitting safely 24/7 amongst the night time predators not to make our life better.

 

How many birds?
How many nests? Describe nests.
How long have birds been laying?

Maybe confine them to the coop for a few days, use fake eggs of some sort.
After they get the idea, let them out again. If they go back to laying where you don't want them to, repeat lock up.