Thumbnails not working

Hi,

I’m having an issue with thumbnails not showing. Instead it’s displaying a full size image. I’ve added add_theme_support( ‘post-thumbnails’ ); into functions.php, but it didn’t solve it http://atv5.mywebsitelead.com/portfolio/. The thumbnails are now resized by css, but I prefer using thumbnails. Any ideas on how to fix this?

Thank you!!!