siegfried, sorry for the late response. is it possible that you(the DBAgent_User) doen't have EXECUTE permissions on MON_GET_DATABASE? That DB2 provided (built-in) routine should work in 10.1.x as well, as far as I can tell.
To confirm this is only a Permissions / Privilege issue and that the routine itself does exist, you can run the following (as DB2 admin)
select funcname from syscat.functions where funcschema='SYSPROC'
If that lists MON_GET_DATABASE, then we can conclude that the missing permissions for your user is the likely cause of the failure.. Hope that helps