timthumb working but not shown when shared on facebook

my timthumb is working fine, and it’s able to generate the thumbnails for my blog (http://tambnguyen.com/). the problem is when i share links on facebook, facebook doesnt seem to be able to grab the thumbnail. when you paste the link, it looks like facebook can parse and grab the thumbnail, but when you actually click on ‘POST’, the thumbnail disappears.

i wish there were a better way to solve this besides including a real <img> in the main content of my blog, but sometimes an entry just doesnt have an image.

the latest entry having problem as of the writing of this question is http://tambnguyen.com/jay-p-morgan-explains-a-three-light-setup/.

please help me.

thank you.