This is my blog http://bloggr.in/
If you try to share the 1st four posts on Facebook, it wont show any thumbnail on facebook. For eg this link http://bloggr.in/2013/10/amazing-illustrations-of-indian-gods/
But if you try to share the 5th link, you will get a thumbnail on facebook http://bloggr.in/2013/09/how-tobacco-affects-the-human-body/
I have recently changed the wordpress theme. Do you think this might be happening because of that only. Also I have tried various plugins that will post thumbnails on fb when they are not appearing and it didnt work.
Any help will be greatly appreciated. Thanks :)