I can't give you a 100% certain answer about why your chameleon didn't use the bin to dig in or whether she could have been saved if you had used a different bin...there are too many things that might be in play in this. Some of this has already been said, but I think repeating it won't hurt.
If the female is healthy and has good husbandry , proper supplements, etc., then she should have all the nutrients needed to produce good eggs and to lay them. Of course, she still needs an appropriate site to lay them in and the peace to get the job done.
What has always worked for me is to put a container of washed playsand that is just moist enough to hold a tunnel in an opaque container at least 12" deep x 12" x 8" in the female's cage once she is sexually mature and leave it there. This way she always has a place to dig to show you that she needs to lay eggs. Most will lay the eggs in this size of a container. However, once they start digging, they can be moved to the trash can or a large rubbermaid bin that has been set up as an egglaying site. The female should not see you watching her while she is digging or she will abandon the hole. If it happens often enough, it will likely lead to eggbinding.
Back to the egglaying...there could be a physical reason such as malformed eggs, uterine deformity, hormones not right, eggs that have grown too big, folicular stasis, etc. that prevented her from laying the eggs. An necropsy would have been the best shot at determining this.
Yankfathom said..."I heard reptile sand works better and not play sand because of the roughness of it. True? "...I have used the same brand of playsand for over 15 years and it has never caused a problem with my chameleons (even if they eat some of it)....its produced by Kings...here it is...
http://www.homedepot.ca/product/king-play-sand-20kg/902209
ijmccollum said..."Does moving the cham from her enclosure to a laying bin cause any interuption in the activity? Reason I ask is that I have thought of doing this as well - sequestering the bin in the shower and closing the door"...
I usually move the female once she has started digging in the container in her cage, but I only move her when she is up in the branches, not when she is in the hole. I will often start a hole in the sand in the bin I move her to as well. If you do put the container in the shower, make sure that if she climbs out of the bin she has a way to get back into it.
Its a shame that even after so many years of chameleons being kept as pets that egglaying is still such a big problem. The study done a couple of years ago was a good start on learning about the hormones, but there is a lot more that will need to be done before there will be some real answers concerning why, even when the husbandry is good and the chameleon is healthy, there are still so many problems getting them to lay.