HELP! Facebook login works partially only

I installed a gallery on my website (ignite gallery). This allows you to make links to pictures in the gallery one by one through facebook (plus the ability to comment and do like).

I would like to publish the gallery only to users who are "login" via facebook.

so I gave permission to the gallery "registred".

my gallery is published to this url.
http://www.matildadisco.it/index.php/ga ... -3-maggio1

if I try to login with facebook using the "login" in the upper right, everything works fine! my gallery is displayed, and I can interact on the photos

If they are not logged via facebook,
If I put the following link in my browser,
http://www.matildadisco.it/index.php/ga ... -3-maggio1
I get redirected to the page
http://www.matildadisco.it/index.php/template/users
in this page, the 'login with facebook' button, DOES NOT WORK!

I think there is a bug, but I can not figure out how to solve it!

can you help?

thanks in advance

Massimo

http://www.matildadisco.it/index.php/template/users

the button with facebook login works ok for me.