Yes, I was attempting to verify the behavior that you were describing by creating an account. Once verified, I was going to try to log in again via LinkedIn to try to get the error message.
The *only* reason you could be getting that error message is if your browser can't connect to linked in. The URL in the image you show is
www.linkedin.com/... and the message shows that your browser can't connect. That all happens *after* JFBConnect has generated the proper URL and is trying to authenticate you. For some reason, the authentication URL is unreachable in your browser. That could be a browser issue (some extension is blocking LinkedIn), a firewall or proxy issue (are you trying from within a company) or a geographic restriction (are you in China or another territory that blocks LinkedIn)?
Either way, there's nothing that can be done within JFBConnect. You'll need to diagnose why that URL can't be reached from where you are. The only recommendations I can give are to try from many different computers and/or browsers to see if the behavior persists in all.
I hope that helps,
Melissa