I'm wondering if anyone has ever experienced this problem. I'm trying to check in online for a flight tomorrow. I'm within the 24 hour window, and I can select my itinerary and continue to check in. On the second screen (where you select the passengers you'd like to check in) the "status" column shows: "We are unable to locate an electronic ticket for this itinerary. Please return to your original place of purchase for assistance and return to united.com for check-in."

I called reservations and they say the electronic ticket matches and everything should be fine. United.com support doesn't know why I'm getting this message and says to just proceed to the airport for checkin.

Any ideas?