Problems with adding category to post in WordPress
===

Any WordPress experts in here who can tell me why the below code will not work, it does not add the post to the selected category. The category has been checked and has correct id.

				// Create post object
  				$my_post = array(
 				'post_title' => strip_tags($cp_auction_title),
 				'post_type' => 'auction',
 				'post_content' => strip_tags($cp_auction_description),
 				'post_status' => 'draft',
 				'comment_status' => 'closed',
 				'post_author' => $current_user->ID,
 				'post_category' => array(422)
  				);

				// Insert the post into the database
  				$pid = wp_insert_post( $my_post );
				
				update_post_meta($pid,'closed','0');
				
				update_post_meta($pid,'shipping',$shipping);
				update_post_meta($pid,'paid','0');
				update_post_meta($pid,'location',$location);
				update_post_meta($pid,'buy_now',$buy_now);
				update_post_meta($pid,'start_price',$start_price);

				$_SESSION['my_pid_pid'] = $pid;				
				wp_redirect(get_bloginfo('siteurl').'/?_post_new_=1&step=2');


Thanks

Rune