If you are receiving the error /usr/bin/crontab permissions are wrong. Please set to 4755 when in the cron section of cPanel, the commands below may correct the error for Redhat/CentOS/Fedora servers.

Log into the server via SSH or the console as root and run:

yum -y install vixie-cron crontabs
chmod 4755 /usr/bin/crontab