If your McAfee activation code isn't working, there could be several reasons for this issue. First, ensure that you’ve entered the code correctly at www.mcafee.com/activate, paying attention to any potential typos or spacing errors. The code might also be expired or already used, which would prevent activation. Additionally, check that you're using the correct region and that your internet connection is stable. If the issue persists, you may need to contact McAfee support for assistance. They can verify the code's validity and help resolve any technical problems.