Ahh.. Didn't copy over the most up-to-date change, which is why you still got the error. However, I just looked at your configuration settings, and enabled the "Automatically Link Facebook Users by Email:" setting.
My assumption is that there is already a Joomla user with the same email address. Please try again, and let me know if you get through. This will associate the Facebook user with the account that already exists on your system.
If it still fails, the next thing that would really help, is the Facebook login information for that user, if you're ok PM'ing it to me to test with.
Thanks,
Alex