The problem seems to be with the folder name. If I install the file by double-clicking the wba file it creates a folder named Caramel light with a space between the words. If I unzip the file to a folder and move the folder into WB the folder is named Caramellight, with no space, and then the skin won't load.

It probably depends on which version of WB someone is running. I think the latest versions handle folder names better than the older builds. It's always best to not have spaces in a filename if it's going to be handled by a web based app like the uploads here are. All WB skins get renamed to have .wba for the extension.  It might take out any spaces too but I'm not sure about that.