trying to do online check-in today. It keep saying I don't have a record because it isn't linked to my MPC. But the MPC account clearly shows my tickets and that's how I can click the check-in in the first place.

Anyway, found out that when you load the manage my booking they indeed does not load your MPC info with it. Click the Frequent Flyers tab and under the information it shows nothing. Just click the "edit" button and don't worry, you won't be editing anything, all of a sudden your account number will be loaded (your number will show after a refresh), and wa-la, you can check-in no problem.

Just thought this might be helpful to others that are having online check-in problems.