Check the fine print for any exclusions or restrictions on the coupon code. Verify the expiration date to ensure the code is still valid. Try a different web browser or device to see if the code works there. Disable browser extensions temporarily, as they might interfere with the code. Clear cookies and site data to refresh the browser. Use incognito or private browsing mode. Contact customer service for assistance. Search for a new working promo code if the current one is invalid.