Did you try the new Playground from Facebook Connect and get the following error:
“An error occurred while registering your site”
This happened to one of our readers, and here’s how we resolved the Facebook Connect Playground error:
For this error to get resolved, you must clear the cache of your browser so that no pre-disposed form data is present. Depending on your browser (you can reply and let me know if you need help) will depend on exactly how you go about doing this.
I’ve written a “how to” for clearing cache on Firefox here >> http://socialmediaseo.net/2009/10/01/fix-slow-f...
Otherwise, for Internet Explorer go to “tools > internet options > click delete in browsing history > then select all check boxes”
For Safari go to “the circle settings icon in the upper right hand corner > click “reset Safari” > select all checked boxes”
For Chrome “click the wrench icon in the upper right hand corner > click on “clear browsing data” > clear all history
For all of the options above, you’ll probably have to re-login to everything, but this should clear out all the browsing cache.
And then go back and retry registering your site at Facebook Connect Playground >> http://developers.facebook.com/setup.php