It sounds as if the tags aren't being set correctly if the share image preview and descriptions are not set correctly.
To do this, you'd need to
1. Enable the 'Open Graph - K2' plugin that comes with JFBConnect. When enabled, JFBConnect attempts to set the image/description/etc tags on the page from the K2 item content.
2. If you want further control of what image or text is set, you'd create an object in the JFBConnect backend > Social Meta > Objects area. (You don't need to create one in the FB dev area).
3. After you set the tags, you'd need to manually re-scrape the page to see if the new tags are set up correctly. You can scrape the page using the
Facebook Sharing Debugger
If those tips don't help, please provide a specific URL where you're seeing the problem so I can the tags on the page.
-Melissa