The main reasons we know of for that message are:
* Your Facebook Page isn't correctly connected to the Messenger bot. Make sure you've properly set the Facebook Page ID in the JFBConnect settings area, as described in our blog post:
www.sourcecoast.com/blog/facebook-messen...omer-chat-for-joomla
* Your Facebook Page is restricted in some way and the current user isn't allowed to access it. The restriction could be regional, age based, or one of many other factors that could be limiting who sees it.
I hope that helps, but if not, let us know and we'll gladly help investigate further.
Thanks,
Alex