Ultimate Facebook only uploads fallback image to Facebook page

Hello there, I am using the Ultimate Facebook Plugin for my site to where members can post on the front-end of the site which includes images. But each time a post is published on my site by myself or a user, the post is forwarded to my Facebook page, however the image is always the same. It is my fallback image which is always displayed, I would like to find a way so that the image posted on the post will be the primary image. Is there a setting I may have misunderstood perhaps? Any help would be greatly appreciated thanks.

Kind Regards

Gary