so even though the original poster is a Diamond Medallion on DL beucase its a LY marketed flight operated by DL he doesn't get his Diamond Medallion upgrade (subject to availability) ?? If when he books another ticket on the same orute if he asked LY to select a DL flight code versus a LY flight Code will that should allow the DL upgrade processor to potentially process the upgrade if space is avialble. On Popular routes like the DL route he is flying there may be 15-20 Diamond Medallions competing for 2-3 upgrades, he could of just not had a high enough fare designator to scoop up the upgrade. You don't always get an upgrade when a lot of people are vying for the same seat, even as a Platinum Medallion.

RC