Problem: Lookup of fields in products or products_description by products_id in the Admin

Solution: change the function file:
/admin/includes/functions/general.php

from approximately lines 3120 to 3138 where it reads:
Code:
////
// return any field from products or products_description table
// Example: zen_products_lookup('3', 'products_date_added');
//  function zen_products_lookup($product_id, $what_field = 'products_name', $language = $_SESSION['languages_id']) {
  function zen_products_lookup($product_id, $what_field = 'products_name', $language = '') {
    global $db;

    if (empty($language)) $language = $_SESSION['languages_id'];

    $product_lookup = $db->Execute("select " . $what_field . " as lookup_field
                              from " . TABLE_PRODUCTS . " p, " . TABLE_PRODUCTS_DESCRIPTION . " pd
                              where p.products_id ='" . $product_id . "'
                              and pd.language_id = '" . $language . "'");

    $return_field = $product_lookup->fields['lookup_field'];

    return $return_field;
  }
To read:
Code:
////
// return any field from products or products_description table
// Example: zen_products_lookup('3', 'products_date_added');
//  function zen_products_lookup($product_id, $what_field = 'products_name', $language = $_SESSION['languages_id']) {
  function zen_products_lookup($product_id, $what_field = 'products_name', $language = '') {
    global $db;

    if (empty($language)) $language = $_SESSION['languages_id'];

    $product_lookup = $db->Execute("select " . $what_field . " as lookup_field
                              from " . TABLE_PRODUCTS . " p, " . TABLE_PRODUCTS_DESCRIPTION . " pd
                              where  p.products_id ='" . $product_id . "'
                              and pd.products_id = p.products_id
                              and pd.language_id = '" . $language . "'");

    $return_field = $product_lookup->fields['lookup_field'];

    return $return_field;
  }
Thanks for catching the forgotten update, torvista ...