SEPM not pussing update to clients

Hi team.

I am facing issue in SEPM 11.0. SEPM manager not pussing update to clients and SEPM manager is updated with the latest definition. All clients are not updated with the latest definition include windows XP and Servers. I have tryed by manuly push the definition by manager but still fail to take update. In Manager some client are showing online status and some are showing offline status.

 I have changed sylink file on 1 client machine ( windows 2003 server) after replacing sylink it is showing on line but not taking update.

Please help to share recommanded setting for SEPM with client.

Any help or suggestions would be appreciated!

Thanks & Regards
Harvansh Singh