I had this same problem, but finally solved it. Unless I missed it the first 7 times I read the directions, there’s a piece of the puzzle missing.
While creating your Facebook app, you MUST check “Website with Facebook Login” below “Select how your app integrates with Facebook” and add your site’s URL. Otherwise, it won’t be able to authorize the app.
Agreed, and it’s a shame. This plugin was exactly what I needed.
