Ultimate Facebook login not working

Hello,

Ultimate Facebook is not working correctly on my website. The registration button works ok, but the login button just opens up a popup that disappears and nothing happens.

Screenshots:
1- http://cl.ly/2K2k450g1p2Y2L0x2S1n
2- http://cl.ly/1A2p462P3l2i2K3m2c3I

You can try for youself in http://acepto.com.br

The registration button is located in acepto.com.br/cadastrar/ and the login button is on http://acepto.com.br/login/

Thank you.