How high are the nesting boxes off the floor now? Some birds will easily flap and fly up higher but it depends on the breed, the bird and the space available for them to flap their wings. Our coop is fairly small, so we have them sitting only a couple inches off the floor..they can just step in. Also, are they open or covered? When we had open boxes, only 2 of our 6 would use them, but since we covered them, they all make use of them.
How old is your hen? Any time after about 20 weeks, you can expect to see some eggs. The first 1 or few can be pretty weird...without shells or thin shells or very, very small. After a week or so, their bodies finally get geared up, tho.
If you can encourage them to get in the nesting boxes it will help. They'll get in and turn around and re-arrange the bedding. They may even sleep in them. Then when the time comes, they'll be more likely to use them. It wouldn't hurt to put a fake egg or golf ball in the boxes as well...this can be a signal to them that it's a good place to lay.
