warning: Parameter 2 to drupal_retrieve_form()

Trabajo con drupal 6.22

Como apunta NITEMAN la version php es importante puesto que es el tipico petardazo del paso de la version 5.2 a la 5.3

En resumen, estoy usando las versiones 6.22 de Drupal y 5.2.6 de php.
Me podríais ayudar con este error?

No encuentro el simbolo & que me comentais en la linea que me indica el error. Os pongo el códifo para ver si lo encontrais porque yo desde luego no.
Gracias por toda la ayuda.

<?php
// $Id: vertical_tabs.admin.inc,v 1.1.2.2 2010/02/03 19:06:46 davereid Exp $

function vertical_tabs_settings_form() {
$form['vertical_tabs_default'] = array(
'#type' => 'checkbox',
'#title' => t('Include new fieldsets in vertical tabs by default.'),
'#default_value' => variable_get('vertical_tabs_default', 1),
);
$form['vertical_tabs_minimum'] = array(
'#type' => 'select',
'#title' => t('Minimum number of tabified fieldsets to show vertical tabs'),
'#description' => t('Non-tabified fieldsets do not count towards this minimum.'),
'#options' => array(1 => t('No minimum')) + drupal_map_assoc(range(2, 10)),
'#default_value' => variable_get('vertical_tabs_minimum', 1),
);
$form['vertical_tabs_node_type_settings'] = array(
'#type' => 'checkbox',
'#title' => t('Expose vertical tabs selection on the edit content type forms.'),
'#description' => t('This feature will not work when adding a new content type and may not detect some fieldsets.'),
'#default_value' => variable_get('vertical_tabs_node_type_settings', 0),
);
return system_settings_form($form);
}

function vertical_tabs_add_node_type_options(&$form, $node_type) {
module_load_include('inc', 'node', 'node.pages');

// Build a psuedo-node for a sample node form.
$node = (object) array(
'type' => $node_type,
'name' => '',
'vid' => 0,
'language' => '',
);

// Build a sample node form to find fieldsets.
$node_form_state = array('values' => array());
$node_form_id = $node_type .'_node_form';
$args = array(
$node_form_id,
$node_form_state,
$node
);
$node_form = call_user_func_array('drupal_retrieve_form', $args);<-------------LÍNEA 45
$node_form['#post'] = $node_form_state['values'];
drupal_prepare_form($node_form_id, $node_form, $node_form_state);
uasort($node_form, 'element_sort');

// Find all fieldsets.
$elements = vertical_tabs_get_form_elements($node_form);
$config = vertical_tabs_get_config($node_type . '_node_form');

// Merge default values and correct non-key-matching values.
// @todo Keep settings for non-accessible fieldsets set by more priviledged users?
$defaults = is_array($config) ? $config : array();
$options = array();
foreach ($elements as $key => $element) {
$options[$key] = $element['#title'];
if (!isset($defaults[$key]) && !empty($element['#group'])) {
$defaults[$key] = $key;
}
}

$form['vertical_tabs_settings'] = array(
'#type' => 'fieldset',
'#title' => t('Vertical tabs'),
'#collapsible' => TRUE,
'#collapsed' => TRUE,
'#description' => t('The selected fieldsets will be rendered as vertical tabs for this content type. The tabs are rendered in the same version as the original form\'s fieldsets.'),
'#group' => 'additional_settings',
'#tree' => TRUE,
);
$form['vertical_tabs_settings']['form_id'] = array(
'#type' => 'value',
'#value' => $node_form_id,
);
$form['vertical_tabs_settings']['fieldsets'] = array(
'#type' => 'checkboxes',
'#title' => t('Include the following elements in the vertical tabs'),
'#options' => $options,
'#default_value' => $defaults,
);

array_unshift($form['#submit'], 'vertical_tabs_node_type_form_submit');
}

function vertical_tabs_node_type_form_submit($form, &$form_state) {
if (isset($form_state['values']['vertical_tabs_settings'])) {
$settings = $form_state['values']['vertical_tabs_settings'];
vertical_tabs_save_config($settings['form_id'], $settings['fieldsets']);
unset($form_state['values']['vertical_tabs_settings']);
}
}