Obviously you have never been pregnant before!

I get a chuckle out of many keepers who think that just because the chameleon is gravid and they can see and feel the eggs, that they should just lay on command. It doesn't work that way. And, yes, I do understand the stress involved because I feel it, too, everytime I'm waiting for a female to lay.
All joking aside, laying eggs (or delivering babies) does not happen just because you think it is time. There is a lot that goes into the timing of laying and in general, they lay when they are ready as long as you don't do things that muck it up.
Has she been restless? I've found that often--not always--my females will be restless for a few days before they lay. Sometimes they will be in and out of their nest box for many days before they lay. That can be normal.
Your cage set up could be problematic. I use coco fiber for my lay bins but I am not working with a species that lays fairly shallow. If you are going to use coco fiber, it needs to be a lot wetter and packed down.
Another breeder talked to me about using a garbage can rather than boxes in the cage. He finds they lay in the afternoon, so he will put females he thinks want to lay in a garbage can with plants and sticks and properly moist substrate early in the afternoon after they've had a chance to drink and warm up a bit. If they don't lay by the evening (or maybe late afternoon?) he puts them back in their cages and repeats the next day. I've done this a few times with females that didn't seem to want to lay in their cage.
If she is bright and alert and eating, I doubt she is quite ready to lay. They usually tell you if you pay close attention to them.