Thanks all. This reservation was made 2 days ago, so it is fairly new, and my company uses a corporate travel agency so I think either one or both of those reasons would explain why I can't change my info from what you have all said.
I'll give it a few days and try again or worst case just request the missing miles after the fact. I don't have status with USAirways (yet) so it isn't that big of a deal. I just don't want to forget to request the missing miles!