Double-check the coupon's expiration date and scope of application. Ensure the coupon is valid for the items in the cart and hasn't expired. Verify the coupon code is entered correctly, without any typos or extra spaces. Check the website's terms and conditions for the coupon, as some may have specific restrictions or requirements. Contact customer service for assistance if the coupon still doesn't work. Try using a different browser or clearing the cache and cookies, as sometimes technical issues can prevent the coupon from being applied.
