Make sure to fill in the email address associated with your Karma account in advance to pre-ordering.
When providing your shipping and credit card details double-check in the Order Summary on the right-hand side that your Karma discount code is indicated.
If not please clear the cache of your browser and try again. If the code still doesn't show please try to place the pre-order through another Internet browser.
If none of the above helps don't hesitate to reach out to firstname.lastname@example.org.