Can’t make seat reservation GoldenPass train Lucerne-Interlaken, June

I have bought what I think are first-class tickets for the Golden Pass rail trip on June 16.  I have been trying for a week to make seat reservations and have gotten the instructions for doing it on the phone app and also online from my laptop.  It has proven to be impossible for me to figure it out.  One reason is that I can’t remember (or find it on the tickets) if they are for a certain time that day.  When I tried to reserve seats, I used several different times, and got the message that they couldn’t reserve seats for us for those times.  Could that mean that those those particular trips are filled up?  Do I have to wait until a certain period of time before the trip to make reservations?

I have been in contact with the SBB.ch by email and, so far, they have just sent me the instructions once more.  I have written them back with our ticket numbers asking if they can check those tickets to make sure the are for the correct train and if they have a specific time.  Still waiting on a reply.  I have tried to attach the top part of our tickets to this post, but message says the files are too large.  The ticket numbers are :

Donna Halter – Ticket ID 147046693862                 Glenn Halter – Ticket ID 782838102901

and am hoping someone can check them for me or tell me how to do it.

Thanks so much!