无法为新的自定义帖子类型注册分类

Question

Running 2 function plugins on the same install. One of them registered custom post type and taxonomy for it no problem. Other one, however, doesn't register taxonomy (post type itself is registered no problem).

Here is the code of post type registration for first plugin (where everything works)

/* Ads Custom Post Type */
/*======================*/
function create_post_type() {
  register_post_type( 'Ads',
    array(
      'labels' => array(
        'name'               => 'Ads',
        'singular_name'      => 'Ad',
        'menu_name'          => 'Ads',
        'name_admin_bar'     => 'Ad',
        'add_new'            => 'Add New',
        'add_new_item'       => 'Add New Ad',
        'new_item'           => 'New Ad',
        'edit_item'          => 'Edit Ad',
        'view_item'          => 'View Ad',
        'all_items'          => 'All Ads',
        'search_items'       => 'Search Ads',
        'parent_item_colon'  => 'Parent Ads:',
        'not_found'          => 'No ads found.',
        'not_found_in_trash' => 'No ads found in Trash.'
      ),
      'public' => true,
      'has_archive' => true,
      'rewrite' => true,
      'hierarchical' => true,
      'supports' => array( 
        'title', 
        'revisions'
    ),
    )
  );
  register_taxonomy("Placements", array("ads"), array(
    "hierarchical" => true,
    "label" => "Placements",
    "singular_label" => "Placement",
    "rewrite" => true
    ));
}

add_action( 'init', 'create_post_type' );

And here is one that doesn't register taxonomy

/* Related Custom Post Type */
/*======================*/
function create_related_post_type() {
  register_post_type( 'Related',
    array(
      'labels' => array(
        'name'               => 'Related',
        'singular_name'      => 'Related Unit',
        'menu_name'          => 'Related Units',
        'name_admin_bar'     => 'Related Unit',
        'add_new'            => 'Add New',
        'add_new_item'       => 'Add New Unit',
        'new_item'           => 'New Unit',
        'edit_item'          => 'Edit Unit',
        'view_item'          => 'View Unit',
        'all_items'          => 'All Units',
        'search_items'       => 'Search Units',
        'parent_item_colon'  => 'Parent Units:',
        'not_found'          => 'No units found.',
        'not_found_in_trash' => 'No units found in Trash.'
        ),
      'public' => true,
      'has_archive' => true,
      'rewrite' => true,
      'hierarchical' => true,
      'supports' => array( 
        'title', 
        'revisions'
    ),
    )
  );
  register_taxonomy("Collection", array("Related"), array(
    "hierarchical" => true,
    "label" => "Placements",
    "singular_label" => "Placement",
    "rewrite" => true
    ));
   }

   add_action( 'init', 'create_related_post_type' );

Here is error code that i get. Not sure though, if it's related to this issue. Could be related to settings page.

[Mon Sep 03 20:09:55.199466 2018] [proxy_fcgi:error] [pid 26021] [client 127.0.0.1:33527] AH01071: Got error 'PHP message: PHP Warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'Related_init' not found or invalid function name in /home/sitedomain/blabla/public_html/wp-includes/class-wp-hook.php on line 286 ', referer: sitedomain/wp-admin/edit.php?post_type=related&page=Related

Answer 1

From codex:

Function register post type

register_post_type( $post_type, $args );

$post_type (string) (required): max. 20 characters, cannot contain capital letters or spaces.

$args (array) (optional): An array of arguments.

Function register taxonomy

register_taxonomy( $taxonomy, $object_type, $args );

$taxonomy (string) (required): The name of the taxonomy. Name should only contain lowercase letters and the underscore character, and not be more than 32 characters long (database structure restriction).

$object_type (array/string) (required): Name of the object type for the taxonomy object. Object-types can be built-in Post Type or any Custom Post Type that may be registered.

$args (array) (optional): An array of arguments.