Me: I'm checking in for the 7:340 am flight to Hong Kong.
Dragon Air: You did not use the first part of your ticket so you cannot use next segment.
Me: Of course I flew fro Chicago to Shanghai yesterday. I am here.
Dragon Air: You did not fly yesterday.
Me: (show passport stamp verifying entry into country yesterday. show boarding pass.)
Dragon Air agent, holding my boarding pass from previous day in hand: You used another ticket. You did not use the first part of this one.
(LOOOOONNNGGG discussion ensues, involving supervisors and my absolute stance that I WILL fly to Hong Kong today.)
Me: (rummaging around for any other evidence, finally finding my lost luggage paperwork from previous day, identifying the flight number.)
Dragon Air: Yes, this shows you flew yesterday.
Good thing I lost my luggage on a non-stop flight. It went to London.