Marketpress Products in Sitewide Tags plugin display

Just started using MarketPress and want to aggregate products through to my sitewide tags blog which is pulling in global posts network-wide.

I found this solution by Boone Georges re adding other custom post types to Sitewide tags.
Drop this code into a new mu-plugins file:
function add_product_type( $allowed_post_types ) {
$allowed_post_types['product'] = true;
return $allowed_post_types;
add_filter( 'sitewide_tags_allowed_post_types', 'add_product_type' );

Unfortunately it didnt work. Wondering if you guys can shed some light?