If you can't make a purchase online with your check card, you might have the same problem I did.
If your purchase requires your ARN, Alien Registration Number, your purchase might be denied if you did not use or have your own ARN at the time you opened your bank account.
If you didn't have your ARN when you opened the account, the bank computer system made up an ARN for you by scrambling the numbers in your passport number. This is the ARN associated with your account. If you enter your real ARN to make a purchase and it does not match the one registered with your account, your purchase may be denied.
So in order to make purchases, you need the "ARN" on file with the bank. Just ask a bank representative the next time you are at the bank. Happy online shopping to you all.