Facebook Connect for Drupal The readme.txt of the Facebook Connect module is seriously out-dated! It really needs a review concerning the FB updates.

Now, the real problem:
I have installed the module, inserted my appID and all that, but when in /admin/config/people/fbconnect I click on 'appearance' I get this fatal error:

Fatal error: Call to a member function getUser() on a non-object in /customers/denotenbalkers.be/denotenbalkers.be/httpd.www/sites/all/modules/fbconnect/fbconnect.module on line 421


When I click on 'app settings' it shows me the notice: "Ensure that you entered valid api keys." but those keys ARE valid. Maybe I'm missing something from the readme? Ex.:

5. Enter the Connect URL on Connect settings tab (e.g. copy value from admin/settings/fbconnect field “Connect url”).
There is no such thing as a connect settings tab!

6. Add your server to the Server Whitelist on Advanced settings tab on Facebook or disable Session Secret Whitelist Exception. 
What am I supposed to add here? Because only the url doesn't work. I suppose an IP-address but I wouldn't know which one.

I've done all the rest, so I'm guessing that that's the problem.

EDIT / SOLUTION:
The problem was that I followed the readme that was on Facebook Connect's project page. The information in there is OUT-DATED and insufficient. The readme that comes with the module itself is the one you should read!
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.