I can't include a screenshot, because there's no error message (and my error log is empty).
I followed the instructions, exactly (I think), and even though Facebook made me a new app and I pasted in the "API" key and the "Secret" key, when I click "Next Step" (or try to click directly on one of the other layers in the accordion), all that happens is the page with the API info animates closed and then re-opens.
My facebook account seems to reflect that the application has been created (I have 3 other facebook apps also, relating to other websites, though frankly I'm quite unclear on how they work).
Facebook did warn me "might take a few minutes to propagate to all servers", but I've been fighting with this thing for almost an hour now. Is there any way to check whether it has properly propagated? The site in question is http://lemonadeheroes.com and the facebook app is called "Lemonade Heroes". I have a facebook page with a similar name; maybe there's a "namespace" glitch? But facebook seemed to approve all my decisions.
HELP?!!? I'm completely stumped.