taxonomie kommt nicht

functions.php

function codex_muse_subcategory_taxonomy_init() {
    // create a new taxonomy
    register_taxonomy(
        'subcategory',
        'page',
        array(
            'label' => __( 'Untermenüs' ),
            'rewrite' => array( 'slug' => 'unterkategorien' ),
            'capabilities' => array(
                'assign_terms' => 'edit_guides',
                'edit_terms' => 'publish_guides'
            )
        )
    );
}
add_action( 'init', 'codex_muse_subcategory_taxonomy_init' );