Join Date: May 2002
Location: Pittsburgh
Programs: MR LT Titanium, AA LT PLT, UA SLV, Avis PreferredPlus, HH Gold, Hertz PC, National Executive, etc.
Posts: 31,650
It's more that AA is not allowing you to check-in online, rather than AA not allowing you to check in.
Yes, you really need to wait until tomorrow and check-in at the airport. This is fairly standard for even moderately non-standard international flights.