Thread:Extension talk:OpenGraphMeta/How do I change og:image in the meta tags?

I've added the extension to localsetting.php and then I clicked 'edit' and added the code. However when I click 'facebook like' it doesn't use the image 'sunset.jpg' and I've checked the meta data and there it hasn't changed the og:image source. How do I use this extension? What am I doing wrong?