Anyone managed to get custom post types capabilities working?

I’ve found a few examples of how to create custom post types but I’ve not managed to get them to work e.g from here

https://justintadlock.com/archives/2010/04/29/custom-post-types-in-wordpress

The problem is capability_type. If I comment it out everything works; if I leave it there the labels disappear.

What on earth am I doing wrong? I’ve stripped the code down to the bare minimum.

add_action( 'init', 'create_my_post_types' );

function create_my_post_types() {
	register_post_type( 'super_duper',
		array(
			'labels' => array(
				'name' => __( 'Super Dupers' ),
				'singular_name' => __( 'Super Duper' )
			),
			'public' => true,
	'capability_type' => 'super_duper',

		)
	);
}