Facebook Thumbnail Problem

So for a while now I've been trying to fix this but with no results. I use the Joomla 3 Game quickstart Template and manage all my articles with K2. The problem is, when I try to share an article to facebook the thumbnail do not generate. When using the sharing debugger I get this message
"The 'og:image' property should be explicitly provided, even if a value can be inferred from other tags."

although when I inspect the article all OG tags are present in the header. I've tryed a bunch of things, i added this piece of code to the item.php file that overides K2

$doc =& JFactory::getDocument();
$doc->setMetaData( 'og:image', 'thegamerslife.eu'.$this->item->image);

Worked for 2 items then nothing again. GK opengraph is enabled, i've tryed all of K2 image sizes for sharing and still nothing. Tryed a variety of OG pluggins, none worked. Linked FB App ID, nothing. Been chathing wiht K2 forum admin and he said if there is maybe extra code to generate og:image by you, the provider? I'm really frustrated with all this and nothing seems to work. Any ideas ?
My website is http://thegamerslife.eu/ (wip)

Hi

Do You have an url to the example of article where wrong image is used ? I'm clicking through and till now I always comae across correct image being attached.