Applied the above solution - modifying the user agents. The procedure that solved the issue was from the facebook developers site.
Go to the following link.
https://developers.facebook.com/tools/debug to determine if Facebook detects your og:image. If not, add some code.
With the new Facebook Open Graph stuff, you can define a thumbnail for that page in your of"head" of the form
.<meta property="og:image" content="[image url]"/>