has anyone figured out how to automatically send out email to customer from Zen Cart once shipping lable printed out? I tried to change $customer_notified to '1', didn't work. and tried to add some code into ShippingZZencart.php, but still not working. Any suggestion?

$message =
EMAIL_TEXT_ORDER_NUMBER . ' ' . $oID . "\n\n" .
EMAIL_TEXT_INVOICE_URL . ' ' . zen_catalog_href_link(FILENAME_CATALOG_ACCOUNT_HISTORY_INFO, 'order_id=' . $oID, 'SSL') . "\n\n" .
EMAIL_TEXT_DATE_ORDERED . ' ' . zen_date_long($check_status->fields['date_purchased']) . "\n\n" .
strip_tags($notify_comments) .
EMAIL_TEXT_STATUS_UPDATED . sprintf(EMAIL_TEXT_STATUS_LABEL, $orders_status_array[$status] ) .
EMAIL_TEXT_STATUS_PLEASE_REPLY;

$html_msg['EMAIL_CUSTOMERS_NAME'] = $check_status->fields['customers_name'];
$html_msg['EMAIL_TEXT_ORDER_NUMBER'] = EMAIL_TEXT_ORDER_NUMBER . ' ' . $oID;
$html_msg['EMAIL_TEXT_INVOICE_URL'] = '<a href="' . zen_catalog_href_link(FILENAME_CATALOG_ACCOUNT_HISTORY_INFO, 'order_id=' . $oID, 'SSL') .'">'.str_replace(':','',EMAIL_TEXT_INVOICE_URL).'</a>';
$html_msg['EMAIL_TEXT_DATE_ORDERED'] = EMAIL_TEXT_DATE_ORDERED . ' ' . zen_date_long($check_status->fields['date_purchased']);
$html_msg['EMAIL_TEXT_STATUS_COMMENTS'] = $notify_comments;
$html_msg['EMAIL_TEXT_STATUS_UPDATED'] = str_replace('\n','', EMAIL_TEXT_STATUS_UPDATED);
$html_msg['EMAIL_TEXT_STATUS_LABEL'] = str_replace('\n','', sprintf(EMAIL_TEXT_STATUS_LABEL, $orders_status_array[$status] ));
$html_msg['EMAIL_TEXT_NEW_STATUS'] = $orders_status_array[$status];
$html_msg['EMAIL_TEXT_STATUS_PLEASE_REPLY'] = str_replace('\n','', EMAIL_TEXT_STATUS_PLEASE_REPLY);

zen_mail($check_status->fields['customers_name'], $check_status->fields['customers_email_address'], EMAIL_TEXT_SUBJECT . ' #' . $oID, $message, STORE_NAME, EMAIL_FROM, $html_msg, 'order_status');
$customer_notified = '1';