How add column in page posts medias

Hi I want to add a column which displays the users roles in this content

This is my code:

add_filter('manage_users_columns', array(&$this,'myusers'));
		add_action('manage_users_custom_column',  array(&$this,'function_column'), 10, 3);
		add_filter( 'group_user_sortable_columns', array(&$this,'column_sortable' ));
		add_filter( 'request', array(&$this,'column_orderby' ));

		//Posts
                add_filter('manage_posts_columns', array(&$this,'myusers'));
		add_action('manage_posts_column_column',  'function_column', 10, 3);

                //Pages
                add_filter('manage_pages_columns', array(&$this,'myusers'));
		add_action('manage_pages_custom_column',  array(&$this,'function_column'), 10, 3);

                //Media
                add_filter( 'manage_media_columns',  array(&$this,'myusers'));
                add_action( 'manage_media_custom_column', array(&$this,'function_column'), 10, 3);   

	function myusers($columns) {
		$columns['myusers'] = __('Views', 'myusers');
		return $columns;
	}

	function function_column( $value, $columnz, $ids ) {
        if ( 'myusers' != $columnze )
           return $value;
        $vars = get_user_meta($ids, 'myusers', TRUE);
        return $this->My_displays[$vars];
	}

In users it works fine but in pages and media I have ‘Missing argument 3 for aclass::function_column’

Thank you