srgmmss on "[Plugin: Jetpack by WordPress.com] Twitter cards doesn't work"

Hi,

I found this topic: http://wordpress.org/support/topic/how-to-update-twitter-cards-meta?replies=5

So, I put this code in my theme function.php:

function tweakjp_custom_twitter_site( $og_tags ) {
	$og_tags['twitter:site'] = '@techsou';
	return $og_tags;
}
add_filter( 'jetpack_open_graph_tags', 'tweakjp_custom_twitter_site', 11 );

But now I have this error message:

https://www.dropbox.com/s/fzxgj2f73jcfts4/Screenshot%202014-01-09%2018.59.22.png

Please, can you help me?
Thanks