If your McDVoice validation code isn’t working, there could be several reasons. First, ensure you entered the code correctly, as even a small mistake can cause errors. The code is valid for a limited time, so check if it has expired. Additionally, each survey code can only be used once at mcdvoice.com. If you’re facing issues, try clearing your browser cache or using a different device. If problems persist, contact McDonald's customer support for assistance. Always double-check your receipt details before entering the code to avoid errors and successfully redeem your reward.