I cannot use my promo code – it says "invalid promo code" at checkout?

Please try the following:

1. Make sure you enter the promo code correctly. Note that promo codes are case sensitive.
2. Make sure the promo code has not been used before. Each promo code can only be used once.
3. Make sure the value of the promo code does not exceed the cart value. Otherwise, checkout may fail as a result.