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