ntpdate is a program different from the net dameon. NTPDate is probably erroring out on boot because ntpd is running on that socket.
From the command line, run
# sudo service ntp stop ; sudo ntpdate -s time.nist.gov ; sudo service ntp start
You could also uninstall ntpd all together (apt-get remove ntp) and add a cron script to use ntpdate every hour or so.
UPDATE
ntp service probably won't have meaningful value for you on this system, so remove that first.
# sudo apt-get remove ntp
Now add the command:
ntpdate -sb time.nist.gov
to /etc/rclocal
Reboot. Should be good at that point.