Facebook sharing problem

Hi everybody
on my website exactly on these page
http://www.istantshoot.it/portfolio-membri/?ug-gallery=gallery
i have a big problem with Facebook sharing, when a new image will be posted the sharing option for that image select a random image.
Maybe a plugin/theme conflict?
Theme used: Optimizer pro latest version
Plugin for member gallery: User Gallery WordPress Plugin
Please help me :slight_frown: