Join Date: Jan 2008
Location: NYC, NJ, Long Island
Programs: DL DM, 1.6MM, UA Silver, NEXUS, SkyClub & AdmiralsClub Lifetime, Bonvoy Titanium
Posts: 6,645
Try a different approach which seems to work OK.
Login and go to Book. Put in Origin, Destinatin, Date, etc and click Advanced Search, Then Click the Use Certificates, eCredits, or Delta GIft Cards.
It'll let you find and select your certificate and take you flight selection with prices. You're good to go from there,