I bought the Staples Visioneer Scanner 8100 with the rebate at the online store.On the rebate it says to ( Tape your original receipt or packaging invoice and the UPC symbol from the back of the product packaging) What do I use for an invoive ? All the receipts that Staples sent me all say stamped in huge words "THIS IS NOT AN INVOICE". Does anybody know what I'm suppose to use as the receipt or invoice? TIA