Why isn't the New Customer discount working?

Please note the following terms of use:

• The NEWCUSTOMER15 promo code can only be used once per Loyalty account
• The promotion code cannot be used in conjunction with any other promotion or discount, and cannot be used on items in the sale
• The promo code cannot be used for purchasing gift cards, gift coins, or special orders
• This promotion is subject to certain product and brand exclusions such as Sézane, Loewe, Jellycat, Maria Tash and Annoushka

More information can be found in the promotional terms and conditions.