There's nothing to call about. There's quite simply no Z inventory (see above for actual inventory from EF). I know it may be hard to believe that ITA/Google code may have bugs, but it's a fact. Again, it's only with the multi-city searches. If you do a simple one-way search on LAX-NAS, it get's it right and see's there is only D bucket inventory on a married segment basis on the route. It's when you do the multi-city search where it screws up and incorrectly looks at the bucket availability flight by flight, rather than on a married segment basis. The $442 fare being quoted is a real Z fare, but it's a LAX-NAS fare (not a combination of LAX-ATL and ATL-NAS fares). Threre's just no actual Z bucket availability on a married segment basis. Think about it for two seconds. Do you really believe there's some combo of two Z fares on that routing that adds up to $442?? Of course not. The cheapest Z fares on LAX-ATL are $579 and they aren't even available on flights in the 6AM - noon window due to time-of-day/day-of-week restrictions.