I am trying to add another field (subtitle) to my already created and existing custom post_type: team (code from functions.php in my **child**theme) <?php /** * Custom Post type register framework */ include(get_stylesheet_directory(). '/inc/acpt/init.php'); add_action('init', 'makethem'); function makethem() { $args = array( 'supports' => array( 'title', 'editor', 'page-attributes', 'thumbnail', 'excerpt' ), 'hierarchical' => true, ); $team = new post_type('team','team', false, $args ); } /** * Initialize the metabox class */ add_action( 'init', 'be_initialize_team_meta_boxes', 9999 ); function be_initialize_team_meta_boxes() { if ( !class_exists( 'team_Meta_Box' ) ) { require_once( get_stylesheet_directory(). '/inc/metaboxes/fisio-metaboxes.php' ); require_once( get_stylesheet_directory(). '/inc/metaboxes/init.php' ); } } ?> And this is the code in fisio-metaboxes.php <?php /** * Include and setup custom metaboxes and fields. * * @category YourThemeOrPlugin * @package Metaboxes * @license http://www.opensource.org/licenses/gpl-license.php GPL v2.0 (or later) * @link https://github.com/jaredatch/Custom-Metaboxes-and-Fields-for-WordPress */ /** * Define the metabox and field configurations. * * @param array $meta_boxes * @return array */ add_filter( 'team_Meta_Box', 'team_sample_metaboxes' ); function team_sample_metaboxes( array $meta_boxes ) { $prefix = '_team_'; $meta_boxes[] = array( 'id' => 'team_details', 'title' => 'Team details', 'post_type' => 'team', // Post type 'context' => 'side', 'priority' => 'high', 'show_names' => true, // Show field names on the left 'fields' => array( array( 'name' => 'Subtitle', //'desc' => '', 'id' => $prefix . 'subtitle', 'type' => 'text' ), ), ); return $meta_boxes; } add_action( 'init', 'team_initialize_team_meta_boxes', 9999 ); /** * Initialize the metabox class. */ function team_initialize_team_meta_boxes() { if ( ! class_exists( 'team_Meta_Box' ) ) require_once get_stylesheet_directory(). '/inc/metaboxes/init.php'; } The problem is that when in the wp-admin i whant to add a new team's post_type post, the post_type doesn't have the subtitle field What am I missing? Edit: In case you Didn't notice I've never done this before. I am following [this steps][1] with no succeed.. [1]: http://www.wpbeginner.com/wp-tutorials/how-to-add-custom-meta-boxes-in-wordpress-posts-and-post-types/ -EDIT- I am also trying like this: $meta_boxes[] = array( 'id' => 'team_details', 'title' => 'Team details', 'pages' => 'team', // Post type 'context' => 'normal', 'priority' => 'high', 'show_names' => true, // Show field names on the left 'fields' => array( array( 'name' => 'Subtitle', 'desc' => 'This is the subtitle', 'id' => $prefix . 'subtitle', 'type' => 'text' ), ), );