Double-check the coupon's expiration date and scope of application to ensure it complies with the usage rules. Verify the coupon code with the website's customer service to see if it is still valid. The website may have changed or canceled some promotions. Ensure the coupon code is entered correctly without any typos. Clear the browser cache and cookies to remove any stored data that might be causing issues. Try using a different browser or device to see if the problem persists. If the issue continues, contact the website's support team for further assistance.
