From what I have found, AA is really good at inputing Alaska numbers here in Portland (probably because it happens soooo often), but is really clueless in most airports outside of Alaska's dominence. Bottom line is that you need to either check in a place where they know what to do, or call and beg you get someone who "gets it." I also recently booked some AA flights on the Alaska site and it worked relatively well, so buying them from from Alaska seems like an option too...sometimes, though, the fares Alaska has for AA are out of this world.