I have not done it with DL (only when it was NWA) and used my worldperks card to book the tickets. I didn't keep track of the miles so it may have not worked but asked for the number. I do know it worked when I did the "fly confirmed for less" because it got me enough points to be able and buy my wife a round trip ticket for a trip she went on. Now that I think about it there isn't a card input for DL when using travelnet. The NW system did. Ill try and see if my points added up for NW and carried over in DL miles.