Site does not work when www is prefixed to URL
My site pickakart.com has been hosted at digital ocean (CENTOS)/ zpanel. This works fine when URL is typed as pickakart.com. However when I type URL as www.pickakart.com this does not work.
I have checked httpd-vhosts.conf at /etc/zpanel/configs/apache
ServerAlias pickakart.com www.pickakart.com
In the zpanel's DNS Manager, CNAME has been set by me as
Host Name TTL Target
www 86400 IN CNAME pickakart.com
What is wrong? Why is is that my site does not work when URL is prefixed with www?