Salvatore,
Sorry for the delayed response to this. Can you go to the JFBConnect -> Configuration area and set the "Enable Debug Mode" setting to "Yes". Then, there may be an error message in the 'blue box' popup that should appear when an action is triggered.
If that doesn't help, can you go to the JFBConnect -> Configuration -> Facebook area and set the "Show 'Login Credentials' in popup" to "Yes", if not already. When "No", that setting can cause some issues with the Open Graph Action button.
If that doesn't help, let us know, and we can help investigate further. Also, if you can post, or Private Message, the URL of the page where the Action button is shown, we can look at the HTML to make sure things look right.
Thanks,
Alex