CPT and taxonomy

$labels = array(
  'name' => 'Colors',
  'singular_name' => 'Color',
  'search_items' =>  'Search Color',
  'all_items' => 'All Colors',
  'parent_item' => 'Parent Color',
  'parent_item_colon' => 'Parent Color',
  'edit_item' => 'Modify Color',
  'update_item' => 'Update Color',
  'add_new_item' => 'Add new Color',
  'new_item_name' => 'New Color',
  'menu_name' => 'Colors',
);
register_taxonomy(
  'color',
  null, //tried array('post', 'myposttype') too, permalinks flushed
  array(
  'hierarchical' => true,
  'label' => 'Colors',
  'labels' => $labels,
  'show_ui' => true,
  'query_var' => 'color',
  'rewrite' => array( 'slug' => 'myposttype/color', 'with_front' => false ),
  'singular_label' => 'Color'
));



function register_cpt_myposttype() {
  $labels = array(
  'name' => 'MyPostTypes',
  'singular_name' => 'MyPostType',
  'add_new' => 'Add MyPostType',
  'add_new_item' => 'New MyPostType',
  'edit_item' => 'Edit MyPostType',
  'new_item' => 'New MyPostType',
  'view_item' => 'View MyPostType',
  'search_items' => 'Search MyPostType',
  'not_found' => 'Not Found MyPostType',
  'not_found_in_trash' => 'Not Found in trash MyPostType',
  'parent_item_colon' => 'Parent MyPostType',
  'menu_name' => 'MyPostTypes',
  );
  $args = array(
  'labels' => $labels,
  'hierarchical' => false,
  'description' => 'My Custom Post Type',
  'supports' => array( 'title', 'editor', 'excerpt', 'author', 'thumbnail', 'trackbacks', 'custom-fields', 'comments', 'revisions', 'post-formats' ),
  'taxonomies' => array( 'color' ),
  'public' => true,
  'show_ui' => true,
  'show_in_menu' => true,
  'show_in_nav_menus' => true,
  'publicly_queryable' => true,
  'exclude_from_search' => false,
  'has_archive' => 'myposttype',
  'query_var' => true,
  'can_export' => true,
  'rewrite' => array( 'slug'=>'myposttype', 'with_front'=> false ),
  'capability_type' => 'post'
  );
  register_post_type( 'myposttype', $args );
}
add_action( 'init', 'register_cpt_myposttype' );


function associate_taxonomies() {
  register_taxonomy_for_object_type('color', 'post');
  register_taxonomy_for_object_type('color', 'myposttype');
}
add_action('init', 'associate_taxonomies');