If your server time isn't correct follow these steps to synchronize it:
Log in to your server from shell and stop ntp daemon:
killall -9 ntpd
Set preferred ntp server:
ntpdate pool.ntp.org
Start ntp daemon:
/usr/sbin/ntpd
Check if your server time and date are correct:
date
Wed Aug 22 11:08:13 CEST 2012