Hmmm.. not sure actually. That does sound like the PHP4 error you'd normally get, but the file you're seeing it in shouldn't even get that error in PHP4.
Can you check to make sure you installed the correct version of JFBConnect for your Joomla installation (looks like Joomla 1.5 from where you posted). Beyond that, I really don't have any great suggestions. If possible, can you Private Message me admin credentials to your site and we can look further into it? You can PM me by clicking the arrow under my picture (<----) and hitting the mail icon.
We don't normally jump right to that stage, but fatal PHP errors are never fun.
Thanks,
Alex