There can be a couple of reasons why you are not able to use your coupon on the Man Matters app. For instance, the code of your coupon may have expired. In such a case, look for a Man Matters coupon that is valid. It is also possible that you have incorrectly entered your coupon code on the checkout page. So, always keep in mind to double-check the code before entering it. Also, we advise you to go through the terms and conditions of the coupon codes before using them as certain coupons can be used for particular product categories only.