Facebook Connect for Drupal
Did you double check that you installed the Facebook PHP library correctly per the README? 

2. Upload facebook-php-sdk library (http://github.com/facebook/php-sdk/) into the libraries folder so that it looks like 'sites/all/libraries/facebook-php-sdk/src/facebook.php'.


The error you are getting looks like it is coming from a library function not in memory.

You can confirm whether this is loaded or not on your admin 'status' page. You should also check the drupal logs to see if there is any more descriptive error to share. 

If its in the right place but not loading, you might want to check this thread:

http://drupal.org/node/1318296

for advice on how to get it to work with the libraries API.