Windows Update GP Settings not Applied to Client PCs

Hi,
I have set up the default domain policy to give my Windows XP SP-1 computers
the four Windows Update Policies relating to SUS. The SUS server is
operating properly. All other AD Policies defined in the ddp are being
applied but SUS-related ones are not. there are no other policies defined
elswhere in AD which might be blocking these. I do not see the WindowsUpdate
keys in the local PCs registry nor are the windowsupdate logs indicating that
the PCs are getting updates from the SUS server. What could be wrong, ?
Cheers,
Bill