Virtuemart manufacturer_id not work on product detail page

[AnthonyWang]

Hi there,
I tried <?php echo $this->product->virtuemart_manufacturer_id; ?> on prdict detail page,but it not work,
i tried many different way,but all not working,please help

Joomla 3.4.8
Virtuemart 3.0.12

[jenkinhill]

Code used in VM productdetails default template is

<?php
      // Manufacturer of the Product
      if (VmConfig::get('show_manufacturers', 1) && !empty($this->product->virtuemart_manufacturer_id)) {
          echo $this->loadTemplate('manufacturer');
      }
      ?>