The {JFBCLogin} tag only shows the Login (and logout button if enabled). It doesn't insert the full JFBCLogin module into that position, which has more features available.
I haven't used the yoologin lately, but, if possible, I'd recommend inserting the JFBCLogin module into this position and mark it as "Registered". Then, when the {JFBCLogin} button disappears when the user's logged in, the full module will display. If that doesn't work for you, let us know, and we can help you manually insert the code to show the user's Facebook avatar.
Thanks,
Alex