Order ui: Notice: Undefined index $strings...

/**
 * Implements hook_i18n_string_list().
 */
function commerce_order_ui_i18n_string_list($group) {
  if ($group == 'commerce') {
    // Allow the order creation help text to be translated.
    $help = variable_get('commerce_order_help_text', '');
    if ($help) {
      $strings['commerce']['order']['help']['create'] = $help;
    }

    return $strings;
  }
}

the return must be inside the if