Why isn't my promotion code working? Why does it not discount the add-ons?

The cart, Create Order and the mobile app all check the same rules, and the message tells the customer which one stopped the code.

• "Isn't valid" or "has expired": the code is switched off, or its Start Date has not arrived or its Expiry Date has passed (the expiry day itself still works).
• "Reached its usage limit": Number of Uses has reached Maximum Uses. Deleting an order gives its use back.
• "Doesn't apply to anything in your order": the order has no product listed under Applies To, or its billing cycle is not ticked under Billing Cycles, or a domain's registration years are not ticked under Domain Registration Years.
• "Needs a qualifying product": Requires lists products the order does not include. Switch on Also allow existing products in account to qualify to let clients who already own one use the code.
• "For new clients only", "for existing clients" or "already used": the New Signups, Existing Client or Apply Once / Client switch applies to this client.
• The discount is smaller than expected: Apply Once discounts only the first qualifying line of an order, and Exclude Configurable Options and Exclude Domains leave those parts of a line out. A fixed amount never takes off more than what can be discounted.
• The discount is not on the renewal invoices: a code takes its discount off the first invoice only. Recur For and Lifetime Promotion are not applied yet.

Edit the code under Settings > Coupons & Promotions. Read Coupons and promotions.