Fbconnect, You must provide a valid callback_url! check your facebook application settings.

I get this;

Canvas Callback URL must point to a directory (i.e., end with a "/") or a dynamic page (i.e., have a "?" somewhere)

So using the sites/all/modules/fbconnect/xd_receiver.html as the instructions tell you won't work.

This page with installation instructions is outdated;

http://drupal.org/node/453420

If you want to get this to work, I would strongly suggest setting up a demo FB Connect site without Drupal so you understand a bit better how it works -- most of the configuration problems are not Drupal module issues. You need to set up a unique FB application for each connect site (and you will not be able access that application through a FB "Canvas Page URL" since your site is not going to be valid FBML).

see: http://developers.facebook.com/connect.php . The comments module, for example, is a very simple to set up and doesn't require a database: http://wiki.developers.facebook.com/index.php/Comments_Box

In any case, the canvas page should generally point to the base directory of your Connect-enabled site and whatever page is generated as the index page must include the FB Connect js library. That page that should include a js function that has the "FB.init" function, which then references the "xd_receiver.html" file. You should make sure that js function points to the correct path for the xd_receiver.html file.

Closing the issue. It was inactive for a long time & it's related to a Drupal Version which is not supported anymore