I am having a very strange problem when I try to share the link of my blog ( http://uscasa.wordpress.com/ ) on facebook. I get a thumbnail of a picture that is no longer part of my site. The picture, which looks like this: http://www.melkonian.org/gal/01.html , used to be the picture I used for the "Blog picture/Icon" in General Settings tab. I believe that is the only place I have ever used that picture. Now however, I have changed that picture. However, when I try to share the link on facebook, I still get that thumbnail without an option to change it to anything else.
The blog I need help with is uscasa.wordpress.com.