HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\AV\Exclusions\ScanningEngines\Directory\Admin
Do you see any folders below Admin it should have a numbered folder which should contain C:\Intetpub, C:\ExchSrv and C:\program files\Veritas.
If not then try updating the policy or rebooting the client just in case the infor is not reflecting in registry.