SEP definition update problem

Hi,

I created a policy for PC to update definition with Symantec Live update server.

I found some PC haven't update from last week. Still keeping 17/12 r4 definitions.

In System Log, I found update ran successfully but no new update on 22/12 2:30 am. But no update was found in Virus and Spyware Protection Logs.

If run LiveUpdate manually in SEP, there is a definition to update.

Please advice.

Thanks