Thanks for coming back to me. Your solution almost worked...it made me think....the form action was just 'advert_Insert.php' when the actual page is 'advert_Insert.php?id_adCo=1'
The intval you gave didn't work, so I thought I would just echo the original query like this:
advert_Insert.php?id_adCo=<?php echo $row_rs_adIns['id_adCo']; ?>
and guess what....it worked!!