I'm having trouble booking a fare on AA.com and wondering if anyone has any insight.

I'm looking at a flight next year from EZE-LAX. It's a ways out so the fares are fairly similar for a long period of time.
I tried Amex Travel and they were returning a result that was a bit less because it was a mixed cabin option - EZE-MIA in business class and then MIA-LAX in economy.
That led to me to try fiddling with the mixed cabin option because, if I can get on the 77W from MIA-LAX, I'm not too concerned about being in business.
At any rate, I tried searching as a multi-city itinerary (EZE-MIA and MIA-LAX) on Amex travel and the right flights popped up but I couldn't book it. It kept giving an error.
I then tried my luck at AA.com and the same options (and some more) popped up but when I tried to book it, it would always error out and not complete the booking.

It seems odd that AA itself would offer unbookable options. Or is it simply a glitch and I might have luck calling in?