I’ve taken this from another site I have made which uses the hierarchical structure and it works. (I have amended to fit your post type)
function register_publications_cpt() {
$labels = array(
'name' => _x('Publications', 'post type general name'),
'singular_name' => _x('Publication', 'post type singular name'),
'add_new' => _x('Add New', ''),
'add_new_item' => __('Add New Publication'),
'edit_item' => __('Edit Publication'),
'new_item' => __('New Publication'),
'all_items' => __('All Publication'),
'view_item' => __('View Publication'),
'search_items' => __('Search Publications'),
'not_found' => __('No Publications found'),
'not_found_in_trash' => __('No Publications found in Trash'),
'parent_item_colon' => '',
'menu_name' => 'Publications'
);
$args = array(
'hierarchical' => true,
'labels' => $labels,
'public' => true,
'publicly_queryable' => true,
'show_ui' => true,
'show_in_menu' => true,
'query_var' => true,
'rewrite' => true,
'capability_type' => 'page',
'has_archive' => false,
'menu_position' => 22,
'supports' => array( 'title', 'editor', 'author', 'thumbnail', 'revisions', 'page-attributes', 'custom-fields' )
);
register_post_type('publication', $args);
}
add_action('init', 'register_publications_cpt');