It could be as simple as didn't wait long enough or needed to be in a different spot. If you like this spot and have caught crappie here then also you can go to the feed store and buy some range cubes to put out before you go or maybe even make a holder out of some PVC, maybe 3" or so and cap both ends. Drill lots of holes and put the range cubes in that and if there is a tree there hang it on that tree. If no tree fine some way to place it there and keep it on spot and if nothing else you will most likely catch catfish, but also a good chance you catch crappie and maybe some other fish as well.
Have been out for that long before and had the bait fish, but nothing biting, it happens. Also been out that long and son out with me in a separate boat, I went home with my wife and he and his wife caught crappie after we left and did well! Sometimes it take more time.
Also don't just fish next to the light, but also out at the edges of the light where it's getting to the darker water.