Hello,
Thank you for posting your question. I'm sorry to hear you are having issues with a CNAME record. Unfortunately, with the information you have provided it's difficult to troubleshoot your issue. We have a good article on how to set up a CNAME record in cPanel. If you follow the guide you shouldn't have any issues.
If you are still having issues, I'd suggest reaching out to support for further assistance. I hope this helps!
Thanks!
Tim S