I have a ticketed TATL-reservation with only DL-coded flights. Right from the beginning I've had my Czech Airlines (OK) gold card in the reservation. It had been entered correctly and preferred seats, etc. were available to me. The Elite Plus status showed as well on the homepage.

Last week I thought I would credit to Skymiles instead so on DL.com I changed my ff to Skymiles instead. That worked just fine.

Rethinking my options I decided I would credit this trip to my original FF with OK anyway. However, now DL.com wouldn't let me change the number back! I have spoken to reservations and what happens is that the card enters just fine and they can see the Elite Plus status but after a couple of minutes they get a message saying "NOAGREEMENT" and the card is removed from the reservation. I have verified that the number they enter is correct (as they see the status and can save it) and they have removed all other references to FF in the profile. Still, Delta won't let me add the OK-number again. Reservations (incl. supervisor) has tried several times but every time the same result. The original booking was made in Amadeus but the agents have tried entering the original ff-number in both Amadeus and Delta's internal system, neither worked.

I can retro-credit and/or add the number at the airport (hopefully) so that is not a big problem. However, without the card in the reservation now I don't get access to preferred seats nor will the status be there for any op-ups or similar.

I have tried making a new reservation with the card and everything works fine. So it is somehow this exact reservation that contains some kind of problem.

Did anyone here experience anything like this or can give me any help what to do?

Cheers