pagina bianca...errore query?

[Lino80]

ciao, mi da pagina bianca.... dalla query:

<?php
  if ( ($action == 'new') || ($action == 'edit') ) {
    $form_action = 'insert';
    if ( ($action == 'edit') && isset($HTTP_GET_VARS['sID']) ) {
      $form_action = 'update';

      $product_query = tep_db_query("select p.products_id, pd.products_name, p.products_price, s.specials_new_products_price, s.expires_date from " . TABLE_PRODUCTS . " p, " . TABLE_PRODUCTS_DESCRIPTION . " pd, " . TABLE_SPECIALS . " s where p.products_id = pd.products_id and pd.language_id = '" . (int)$languages_id . "' and p.products_id = s.products_id and s.specials_id = '" . (int)$HTTP_GET_VARS['sID'] . "'");
      $product = tep_db_fetch_array($product_query);

      $sInfo = new objectInfo($product);
    } else {
      $sInfo = new objectInfo(array());

      $specials_array = array();
      $specials_query = tep_db_query("select p.products_id from " . TABLE_PRODUCTS . " p, " . TABLE_SPECIALS . " s where s.products_id = p.products_id");
      while ($specials = tep_db_fetch_array($specials_query)) {
        $specials_array[] = $specials['products_id'];
      }
    }
?>

come faccio a stampare a video per capire perchè mi da pagina bianca?

grazie