That might be why my facebook login didn't work when I tried it on a non Fb site. I suppose I could login direct but I haven't been in my page* for ages. I only have it to enable interaction with a couple of campaign sites.
*Not in my actual name of course, I'm not silly and I told my daughter to shoot me if I ever signed up. I'm legally entitled to the two names I'm signed up as, it's just nobody knows me as that name ;-)