Try this code instead –
//* Customize the entry meta in the entry header (requires HTML5 theme support)
add_filter( 'genesis_post_info', 'sp_post_info_filter' );
function sp_post_info_filter($post_info) {
$post_info = 'By [post_author_posts_link] [post_comments] [post_edit]';
return $post_info;
}
This is what I’m using on this site.
Doing it this way allows you to add whatever shortcode you want. More info – http://my.studiopress.com/snippets/entry-header/
I think the other code you posted is for older Genesis Themes, the one I just posted is for HTML5 Genesis Themes, so it should work. Let me know