Not sure if you are confusing terms, but the only packages that can be tracked via USPS are Express Mail, which usually cost a minimum of about $15 to ship.
On the other hand, a "Delivery Confirmation", available with Priority Mail for about 75 cents, is exactly what it says-- verifies that the item has been delivered. The catch is that it could be delivered to the wrong address, 2000 miles away, but it will still show up as being delivered!!!
Perhaps you ordered Delivery Confirmation/Priority Mail when you meant to order Express Mail w/Tracking.