I offer combined shipping discounts and have followed the eBay instructions for setting up a flat fee shipping rule with combined shipping discounts. However, when I sell multiple items to a buyer, my invoice to the buyer for combined items sold does not apply the combined shipping rule (flat fee for first item, $2 for each additional item purchased within 7 days). I have followed the eBay instructions when preparing my listings but I note on the listing form there is no place to add the shipping discount information for combined shipping. What am I doing wrong?