Problems using WP Fb Auto Publish after installation

hello Guys after installing WordPress Facebook Auto Publish i hv notn been able to use it for the past three weeks now. when i go the settings and enter the Facebook APP IDD and Secret key and click Authenticate beside the secret key i get the message.
{Given URL is not allowed by the Application configuration.: One or more of the given URLs is not allowed by the App’s settings. It must match the Website URL or Canvas URL, or the domain must be a subdomain of one of the App’s domains} pls is dier anyone who has a thought on dis pls.