Notice: Undefined property: stdClass::$data in _fb_social_comments_seo() (regel 288 van ...?

Hi,

I installed facebook social plugins 7.x-2.0-beta4

When I look at my website I get this message:
However when I refresh the page this message disappears...

Notice: Undefined property: stdClass::$data in _fb_social_comments_seo() (regel 288 van /var/www/vhosts/drakenbloedboom.com/httpdocs/sites/all/modules/fb_social/plugins/fb_plugin/comments.inc).
Warning: Invalid argument supplied for foreach() in _fb_social_comments_seo_view() (regel 301 van /var/www/vhosts/drakenbloedboom.com/httpdocs/sites/all/modules/fb_social/plugins/fb_plugin/comments.inc).

What can I do to resolve this issue?
Regards
Mark