Originally Posted by
matthilein

Thanks to all of you for your quick responses.
1. My Flying Blue does not have any information regarding the return flight. Outbound flight was fully credited.
2. No upgrades on the VS flight.
3. When booked on Delta.com, the flight was sold as DL9553 (with an asterisk stating that this flight was operated as VS fit 25).
4. I had a single (Delta: 006) ticket number for all flights.
5. Skymiles account shows the flight for 22 November as DL4376 (posted 26 November) but, the ticket number field is empty (see attached screenshot).
I have written to Delta but no response yet.
DL9553 is the KLM AMS-DUS flight you flew.
The fact the ticket number is missing is weird. You should be getting miles regardless. However it's possible they didn't get your fare class if they didn't get ticket number. If they didn't get that, they can't even credit using the mileage based method. Note reward method says null, this to me means there's an error and it doesn't have info needed and is erroring out.