Help using #autocomplete_path please

I am working to have #autocomplete_path return a valid entry based on a $node->title from another type node. I have based everything off examples:
http://api.drupal.org/api/function/node_example_form/6
http://api.drupal.org/api/function/user_autocomplete/6

some sections of code..

// section of menu
  $items['art/autocomplete'] = array(
    'title' => 'Autocomplete art',
    'page callback' => 'artist_autocomplete',
    'access arguments' => array('access administration pages'),
    'type' => MENU_CALLBACK);

// section of form
  $form['art_artist'] = array(
  	'#type'=>'textfield',
  	'#title'=>'Artists Name',
  	'#autocomplete_path' => 'art/autocomplete',
        '#reguired' => TRUE,);

// the autoreturn function
function artist_autocomplete($string = '') {
  $matches = array();
  $result = db_query_range("SELECT title FROM {node} WHERE LOWER(title) LIKE LOWER('%s%%') AND LOWER(type) = 'artist'", $string, 0, 10);
  while ($artist = db_fetch_object($result)) {
    $matches[$artist->title] = check_plain($artist->title);
  }
  print drupal_json($matches);
}

As I type, the autocomplete works great and I have a complete form when I submit. But, when I preview the form, the textfield is blank. Or, if I elect to save the form, the value is empty. If I call the url, I get { "Value" : "Value" } in the returned page.

I would be grateful for any pointers to help me figure this one out.

Thanks!