I believe this is a common problem for many that the wordpress post when posted on facebook wall does not show a thumbnail picture. It affects me badly because mine is a food blog.
My situation is slightly worse. Sometimes the thumbnail appears on the fb wall, sometimes it doesn't.
Or when doing a preview, it appears. And when I finally publish, the thumbnail picture disappears. It's frustrating.
Previously had no such problems until I upgraded WordPress. Can somebody help?
My site is http://DanielFoodDiary.com