There are a few reasons this could happen. One possibility is not quoting your membership number during your purchase or name mismatch, a membership number mismatch, ineligible fare class and other similar issues.
It is also possible that your flight was ineligible for earning Status Points or Asia Miles. To confirm you are able to earn from a particular flight, please check the Status Points or Asia Miles information during the booking process and on the Manage Booking page once you’ve booked your flight.
To avoid missing out on Status Points or Asia Miles due to name mismatches, please make sure that the name on your passport, ticket and membership profile all match each other exactly.