Problem with Sidebox

[autoace]

Can anyone tell me why this code is not working. I installed the code from this tutorial as directed and its not working (shopping cart sidebox should *ONLY* display on the checkout page).

switch (true) {
    case (SHOW_SHOPPING_CART_BOX_STATUS == '0'):
      $show_shopping_cart_box = true;
      break;
    case (SHOW_SHOPPING_CART_BOX_STATUS == '1'):
      if ($_SESSION['cart']->count_contents() > 0 || (isset($_SESSION['customer_id']) && zen_user_has_gv_account($_SESSION['customer_id']) > 0)) {
        $show_shopping_cart_box = true;
      } else {
        $show_shopping_cart_box = false;
      }
      break;
    case (SHOW_SHOPPING_CART_BOX_STATUS == '2'):
      if ( ( (isset($_SESSION['cart']) && $_SESSION['cart']->count_contents() > 0) || (isset($_SESSION['customer_id']) && zen_user_has_gv_account($_SESSION['customer_id']) > 0) ) && ($_GET['main_page'] != FILENAME_SHOPPING_CART) ) {
        $show_shopping_cart_box = true;
      } else {
        $show_shopping_cart_box = false;
      }
      break;
    }


  //if ($show_shopping_cart_box == true) {
  if ($this_is_checkout_page) {
    $show_shopping_cart_box = true;
  } else {
    $show_shopping_cart_box = false;
  } {
    require($template->get_template_dir('tpl_shopping_cart.php',DIR_WS_TEMPLATE, $current_page_base,'sideboxes'). '/tpl_shopping_cart.php');
    $title =  BOX_HEADING_SHOPPING_CART;
    $title_link = false;
    $title_link = FILENAME_SHOPPING_CART;

    require($template->get_template_dir($column_box_default, DIR_WS_TEMPLATE, $current_page_base,'common') . '/' . $column_box_default);
  }