Hi Paul,
We could check this :
1- On ITCM Agent machine in files DSM\logs\TRC_CF_REGISTER_*.log could you see a line like see :
141016-12:23:45.9491143L|001572|000007a0|cfRegister|cfRegister | |000000|NOTIFY | ITRMAgent::registerUnitFullAgent: Unit . registered!
or do you see an error message during registration of Unit . ?
2- Execute this command on DOMAIN :
cserver dump
and check in file DSM\ServerDB\common\master\hwdb.dump.txt if the missing hostname appears in the file.
3- Then check on DOMAIN if the missing hostname appears in files :
DSM\logs\systemengine*.log
Thanks.
Regards,
Jean-Yves