Not showing facebook connect button with Facebooker 2.0

I'm developing a rails application with Facebooker 2.0, my problem is that the facebook login button only appears when the user's in not already logged in in his facebook account, if the user is logged in, it disappears.

I'm using this code to show the button:

<%= fb_login_and_redirect("/users/create_facebook_user", :perms => 'email,user_birthday,offline开发者_Python百科_access') %>