If you extended the schema by using ExtADSch, review the ExtADSch.log. There are several ways to check but this is probably the easiest.
The CN=Systems Management requires the accounts for the
SMS server and or the system account created for SMS3 to
have more than Full Control granted. It requires that you
go to Advanced, Permissions and grant Full Control to this
object and all child objects to allow the
SMS_Heirarchy_manager to function correctly.
Found the above just looking around on google groups too. Might be something to check out.
Ed