MomADAdmin is not extending Active Directory on Child domains. The problem occurs in a environment where SCOM is installed in one domain monitoring other domain. Within SCOM the following error is shown: MomADAdmin not run
To successful run momadadmin you need to add to both parameters MomAdminSecurityGroup and RMS-Server the domain prefix.
MomADAdmin.exe ManagementGroupName Domain\MomadminSecurityGroup Domain\RMSServer TargetDomain