I've run into this problem on a couple of plugins - Cumulus was the other one.
Most plugins have a folder structure, after unzipping, that goes folder/folder/nowthesubfoldersandfiles.
Usually WP seems to be fine with this, but occasionally it goes blind.
If you've uploaded a plugin and WP isn't listing it, you need to get read of that main folder so that the directory structure on your server is folder/nowthesubfoldersandfiles.
I ran into the exact same issue with a plugin called Cumulus. In that case and in the case with this plugin, I just needed to move that first subfolder (which is just a duplicate of the top folder, anyway) directly into the plugin folder.