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It seems that Facebook's login changed on facebook's part.
A warning message is shown when trying to login. (the left login)
I added a new login made on FB and that works. It needs an api to Joomla to set joomla to logged in.
On FB Developers this message is shown: All apps are being upgraded to Graph API v2.0 or above. Learn more.
The nice thing about the new button is that you can see after login who of your FB friends are on your site also!