This sometimes happens when fare classes are added or changed and the partner hasn't updated their handling of it for whatever reason.
Email your boarding pass, receipt, and Mileage Plan #/details to
[email protected]. It may get rejected as already posted, in which case you'll need to have BA unpost it and resubmit to AS.
See
Miles posted to BA instead of AS - fixable?
(will ask mods to merge this into that thread)