NTP error message in Server Admin …

I just can’t seem to get NTP working. The Xserve gives me an ‘error while writing settings’ error every time I try to ‘use network time server’. I’m using the Date/Time settings in Server Admin/Settings. Firewall is not started but i have added four rules to allow 123 requests out and 123 traffic in, all to the IP of my Xserve. The Xserve is set for NTP in Advanced.

Closing and relaunching Server Admin seems to get rid of the error and accept the changes, but ntpq -p gives me this (Xserve) :

remote refid st t when poll reach delay offset jitter
==============================================================================
time1.euro.apple 0.0.0.0 16 u – 64 0 0.000 0.000 4000.00

Incidentally, me desktop Mac is pointing at the Xserve, the Firewall is started with appropriate ports enabled, including 123 for network time, and in Terminal ntpq -p gives me (client Mac):

remote refid st t when poll reach delay offset jitter
==============================================================================
xserveg51.burto time2.euro.appl 2 u 497 68m 40 0.781 -0.541 0.008

which indicates the broadcasts are getting through.

???