wont defrag

hey, i just noticed my newly installed XP wont dfrag when i click analyze or defrag it just doesnt do anything. btw i edited my serviced,like which ones should run and which shouldnt. i do this to all my computer so i think it the culprit but which service needs to be on so i can defrag?

Check to make sure the Remote Procedure Call (RPC) service is set to "Automatic", and is started. Quite a few system components rely on this service being started.

its on but RPC Locator was off so i turn it on and now it works