The exact same thing happened to me in SFO last month and I called reservations from the ticket counter and handed the gate agent my cell phone to talk with the phone agent that had a clue, who then reluctantly put me on the standby list. I called 800 WE CARE but apparently a memo hasn't gone out to make sure everyone knows the policy. It's annoying that gate agents, who work for CO full time, know less about the policies than the passengers. It would be nice if CO could make sure everyone is on the same page here.