ANC RED-EYE

I have an upcoming flight for which I checked EF and found an inventory of 4 C seats in the awards and upgrades section, searching for the individual leg. I called the number provided, gave my PNR and indicated the leg I wanted to apply the upgrade to. She indicated that the flight (and in fact no flight in my PNR) had any upgrades available. Am I misunderstanding something here, or did I not get a good agent? Also, this is for DFW - ANC - not sure if things work differently for domestic than for international? (I know, perhaps not the best use of them, but as I forecast travel, I'm not confident I'll have a better use, so was thinking that confirming now is better than hoping for something better later and ending up wasting it).

ETA - decided to have her do nothing; she volunteered to waitlist it. Just told her I would look for other opportunities (and what I really meant was that I'd HUCA). It was an unnecessarily long call; not sure why it takes them so long to verify if space is available, but the second agent did confirm that space was available and applied the cert. So, I guess the first agent was just clueless? Seems like not an ideal person to have answering that number.