@Jordi I ran one of your posts through Facebook's debugger:
See the warning there? I suspect that's why your posts aren't being Publicized. Since your site's og:meta tags are being output bu Yoast's SEO plugin, I don't know how you can fix this error, so you should ask in Yoast's support forum:
http://wordpress.org/support/plugin/wordpress-seo
Once you are able to tun your posts through the debugger without any errors, then try Publicizing your posts again and let me know if it works or not. Thanks!