FYI I'm having the same problem finding some of the AS/AA code-shares... the AS webstie doesn't even offer MIA as a destination...
When I search the AS website, or travelocity, for AS1662 MIA/SEA - (7:50a/11:24a 767-300) it also doesn't display as a valid flight.
FYI I am getting these flight numbers and segments from the AS electronic timetable.