Avatar showing when I want featured image to show in Facebook links

When I link to a page from my blog to Facebook, the featured images will appear in the image to choose for the FB post. But when I link to a post, only my personal gravatar appears. Can anyone tell why and is there a way to change this?
My Facebook Fanpage
And the post I’m trying to link. Sorry, I can’t be more specific with the FB page link, but you should be able to see what I mean.

Thanks for any help!