Why won't Twitter validate my card?


Here’s an example of a page - http://rugbypunt.com/tigers-v-cowboys-preview-nrl-rd11/

Whenever I try to validate a Twitter card for my domain via Easy Social Share Buttons I get rejected immediately. But I’ve seen other users post links to my site and the image and preview works just fine when they do it. But when I share links it’s just a link.

When I attempt validation it says:

INFO: Page fetched successfully
INFO: 25 metatags were found
INFO: twitter:card = summaryimage tag found
WARN: Not whitelisted

Is there something wrong with my site code? I’m not a programmer so I’m not sure if I’ve missed something