Custom post type Feeds don't work

I try to see the feeds for a custom post type (news) at this adress

/?feed=atom&?post_type=news

but strangely the feed shows the standard ‘post’ archive and not the ‘news’ post_type archive. I can’t understand why. This happens for all the feed types (atom, rss and rss2).
Here’s the code for the setup of the post type, maybe I’ve done some mistake writing it.

register_post_type( 'news',
		array(
'labels' => array(
	'name' => __( 'News' ),
	'singular_name' => __( 'News' ),
	'add_new' => __( 'Inserisci nuova' ),
	'add_new_item' => __( 'Inserisci nuova news' ),
	'search_items' => __( 'Cerca news' ),
	'not_found' => __( 'Nessuna news trovata.' ),
),
'public' => true,
'menu_position' => 6,
'map_meta_cap' => true,
'supports' => array('title','editor','thumbnail'),
'taxonomies' => array('post_tag'),
'capability_type' => 'news',
'has_archive' => true,
'capabilities' => array(
[...cut...]
),
		)
	);