ntpdate can't adjust the clock

Hi I have set up the xntpd to get time from an time-server, and I have opened the firewall also, so that there is communication between our server and the time server. But when I start the "rcxntpd start", and follow the /var/log/messages, I get the following line: Mar 6 00:20:26 sundecor ntpdate[2363]: Can't adjust the time of day: Invalid argument I can't find any reason for this, and the clock is not adjusted as it should be.. Where to look for this one? Jaska.