Ticket number booking class etc. also has to be correct. A while ago I had a flight which I couldn't claim, but when I look closer at the ticket I could see that the booking class changed when the flight was rescheduled and with the new booking class it worked. Also be aware that the booking class on your boarding card might not be the same as the one on the ticket, and it's the one on the ticket which count.

Try search this forum. There is another tread regarding retroclaim, where the mail address is mentioned. It's ebretro or something similar. Otherwise, use the custom feedback form. It worked in the past for me although I now a days write directly to the diamond support mail address. They can fix everything.