I am having a similar issue. After adding the URL for the web app and saving, the address line provided by Facebook, after filling out their form according to the tutorial, yields an error "cannot be displayed in this frame. When I open to a new window, the game works. I am using letterbox scale with 640 x 480. I have tried using different extensions for the hosting site that are mentioned in the tutorial, but no luck. My game works fine on it's own, hosted from GoogleDrive. I want to add that the latest tutorial, which does not seem to have been updated for at least a year and is not inline with Facebook's current dev layout, instructs your to submit your page in order for it to work, but Facebook will not approve submissions until your app has a high user rating. This seems circular.