Field name not shown in an error messages (required field is empty)

Hi, Sorry I cannot test this, because I patched this on my own - besides some other custom changes - and we're in productivity stage now. But as far I can see, there is no big differnce and mine is working fine:

  $prefix_pre = '<div class="form-item"><label for="edit-title">'. t($element['#title']) .':';
  if ($field['required']) {
    $prefix_pre .= '<span class="form-required" title="'. t('This field is required.') .'"> * </span>';
  }
  $prefix_pre .= "</label>\n";

  $prefix_pre .= "<div id=\"multiselect_labels\">\n";
  $prefix_pre .= "\n</div>\n";
  $prefix_pre .= "<div id=\"multiselect_available\">";
  $prefix_pre .= _multiselect_html_for_unselected_box_start($unselfield, $element['#field_name']);
  $prefix_options = _multiselect_html_for_unselected_box_options($unselected_options);
  $prefix_post = "</select>\n</div>\n";
  $prefix_post .= _html_for_buttons($element['#field_name']);

  $element[$field_key] = array(
    '#type' => 'select',
    '#title' => $element['#title'],
    '#description' => $element['#description'],
    '#required' => isset($element['#required']) ? $element['#required'] : $field['required'],
    '#multiple' => isset($element['#multiple']) ? $element['#multiple'] : $field['multiple'],
    '#options' => $selected_options,
    '#size' => 10,
    '#prefix' => $prefix_pre . $prefix_options . $prefix_post,
    '#suffix' => "\n</div>\n",
    '#attributes' => array('class' => "$selfield multiselect_sel", 'id' => $element['#field_name']),
    '#default_value' => isset($element['#value'][$field_key]) ? $element['#value'][$field_key] : NULL,
  );