I migrated timesync over to NTP via imanager. When I did so I got an
error regarding the keys. I made changes to the key after reading a white
paper and all my servers synch'ed up. After about a week I started
getting the following error on my client servers:

Xntpd is unable to service the time request from ipaddress.
Ensure that you have a valid key for this operation.

If I unload XNTPD.nlm on all servers and reload they synch fine. Then
after a week or so the error pops up again. I checked the ntp.conf files
on all servers and this is what is in there:

enable auth monitor
keys sys:\etc\ntp.keys
trustedkey 33
requestkey 44
controlkey 55

In the keys file:

# key id key type key value
33 M pass1
44 M pass2
55 M pass3

Any idea why the error keeps coming back?