Can't Load jQuery UI in Admin Panel

The following doesn’t load jquery-ui-sortable, even though it should, (you can replace jquery-ui-sortable with any portion of jquery-ui and it won’t work) however it will work with scriptaculous.

What gives? Can someone help?

function my_admin_init()
{
	wp_enqueue_script('jquery-ui-sortable');
}
add_action('admin_init', 'my_admin_init');