[Plugin: NextGEN Scroll Gallery] No thumbnail when I link posts to Facebook

Hey there..I use scroll gallery on my photography website adivarekar.in.
Every time I link a post on facebook, no thumbnail or description shows up, just the link text. Almost all my posts have a featured image.

Is there anything I can do to get a thumbnail when I’m sharing my posts on facebook?

http://wordpress.org/extend/plugins/nextgen-scrollgallery/