the hidden field is set to use the $row_WADAproducts['ProductImage'] value.
this is the same value you have used for the default file.
if it doesn't work for the hidden element, i don't see why it would work for the default file....
The correct method is to bind the hidden element to the recordset value and use the hidden element as the default file.
how are you checking this? are you looking in the page source, that is the only way you will see if the field has a value or not.