Post comment with facebook like button doesn't

Question

Im tryng to use the XFBML implementation of the Like Button, as it is described in the facebook social plugin page

The like button appears and works fine (it asks for a confirm action, but it works ok).

When i press the like button, a new dialog comment box popups that lets me add some comment to appear to my wall. However, when i press the "post to facebook" button, nothing happens and the popup dialog remains there. Finally, the comment doesn't appear to my facebook wall.

Any help??