Why is the system asking for payment although I used an authorization code?

Did you try using two authorization codes in one order? Authorization codes have to be used separately, so you will have to place two separate orders for two authorization codes.

If you already checked out and have been charged, please contact us directly at materialorders@icisf.org with both authorization codes and course registration number (and order number if possible): We can retroactively apply the code and process a refund.