Our discount codes are only valid for one purchase and on full price items. In other words, our discount codes does not work on sales items and you will also not be able to use it when it has expired.
If you have made sure that your order match all of the requirements above but your discount code still does not register on your purchase, please contact our customer service with your order number and the discount you are trying to use.
They will be able to help you given that your discount code is valid for your order!
Please note that there are sometimes exceptions such as super campaigns or special offers when some discount codes are valid on sales items.