up2date failed on WS4.0 after upgrade

[yasushi at cabm.rutgers.edu]

Hi, I just upgraded one WS3.0 box to WS4.0 (U2).
And up2date failed with following errors:
Could someone advise me what is wrong ?
It looks like missing some rpms, but could you find any yet.

Thanks,
yasushi

[root at bmw ~]# up2date
Traceback (most recent call last):
  File "/usr/sbin/up2date", line 27, in ?
    from up2date_client import repoDirector
  File "/usr/share/rhn/up2date_client/repoDirector.py", line 5, in ?
    import rhnChannel
  File "/usr/share/rhn/up2date_client/rhnChannel.py", line 10, in ?
    import up2dateAuth
  File "/usr/share/rhn/up2date_client/up2dateAuth.py", line 5, in ?
    import rpcServer
  File "/usr/share/rhn/up2date_client/rpcServer.py", line 23, in ?
    from rhn import rpclib
ImportError: No module named rhn