This plugin works with my 2 previous sites since it is really good, however, installing a new one seems to be impossible. It could not verify apps.
It gives this feedback:
Facebook returned an unexpected error: Error validating application.
Try to resolve this issue, update the plugin or inform the author about the problem.
[Error occured at line 557]
Your connection options could not be validated.
AND THIS ONE:
Some or all access permissions are missing. Please click the button Grant access rights! and authorize the plugin to post to your Facebook profile or page.
[Error occured at line 774]
Your page or profile's access permissions could not be verified.
Apps are right. I made it sure the app are all true since its not my first time to use this one. But it seems not working. 2 days now.