VAT number on attached PDF invoice

-- HikaShop version -- : 3.0.1
-- Joomla version -- : 3.6.5
-- PHP version -- : 7.0

Hi Hikashopteam,

I like to add the VAT number into the attached PDF invoice.

But I don't know how, I tried 3 different way's but none of them give the VAT number in the invoice.
Could you please give me a hint.

<?php echo 'VAT ID Billing address: '.$oneAddress->address_vat; ?><br/>
<?php echo 'VAT ID Billing address: '.$addresses->address_vat; ?><br/>
<?php echo 'VAT ID Billing address: '.$address->address_vat; ?><br/>