That error is almost always caused because every step of the
WindowsLive setup guide
was not followed. Most importantly, verify step 5, but check them all to make sure.
Another option to try is setting the "Disable SSL Verification" in the JFBConnect configuration area to 'Yes'. Some servers are not updated to be able to verify the SSL certificate provided by WindowsLive. That setting will bypass the check.
Can you send us pictures of the Basic, API and App sections of your WindowsLive app configuration? We'll need to see what's configured there to understand what may be wrong. Also, if you can Private Message me admin credentials for your site, I'll gladly take a look at your PHP and JFBConnect settings to see if there's any issues I can find.
You can PM me by clicking the mail icon under my name to the left.