I am trying to use Award Accelerator (actually Premier Accelerator) on a existing reservation. I didn't seem to get the option when I booked the flight.

I went to this page on United's website and clicked Buy Now. It takes me to the reservation page but I don't see any option.

It's an IAD-SFO-IAD flight. I noticed that it says the option is only available on "qualifying" flights. Possible that this isn't qualifying? Hopefully I'm missing something.

Thanks

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