Register with Facebook ERROR message

Anyone knows how to fix Ultimate Facebook Plugin - Register with Facebook configuration issue?

I get the following message when I click on Register with Facebook.

"Unable to load the registration form for WEBSITE. You may have previously blocked this app on Facebook. Go to your Facebook privacy settings to unblock this app. (Error: Missing 'redirect_uri' query parameter.)"

I created a new app, updated the settings with the new app info and nothing.