In detail section A (where the items information is displayed) add logic to suppress if the lot/serial number is NOT blank
add:
**OR _
{SO_InvoiceWrk.LotSerialNo}<>""""**
here is the full suppression logic for detail section a
**formula = {SO_InvoiceWrk.ItemType} in array ("""", ""4"") or {@AllowExpandedItemCodes} = ""Y"" or _
PreviousValue({@InvoiceNoLineNo}) = {@InvoiceNoLineNo} OR _
{SO_InvoiceWrk.QuantityShipped} = 0 OR _
{SO_InvoiceWrk.LotSerialNo}<>""""**