Hello FT'ers!

I am trying to buy an award ticket for Mrs.FoT
BOS-SFO-ANC-BOS
I checked on Carlson Wagonlit and found there was availability. Tried booking on nwa.com, but it didnt help and asked to call the Elite line.

The BOS-SFO leg was available, so was the ANC-BOS.

The phone rep was helpful, but she could not find any availability on SFO-ANC. She said there was a CO flight, but it tried sending her via Houston! And the system wasnt letting her get around that.

I confess some ignorance here, so could someone tell me why the SFO-ANC flights I saw were not eligible? Is this because of specific fare buckets not being available? I asked the lady on the phone and she insisted that award ticket availability had nothing to do with fare buckets

Delta Airlines Flight: 1518
SFO-SLC
Cabin class: F9 A9 Y9 B9 M9 H9 Q9 K9 L9 U9 T9
SLC-ANC
Cabin class: F9 A9 Y9 B9 M9 H9 Q9 K9 L0 U0 T0

Alaska Airlines Flight: 2474
SFO-PDX
Cabin class: Y7 S7 B7 M7 H7 Q7 L7 V0 K0 G0 T0
PDX-ANC
Cabin class: F0 U0 Y7 S7 B7 M7 H0 Q0 L0 V0 K0 G0 T0

Any input and advice on how I might be able to make this reservation would be very much appreciated.
Cheers,
FoT