No log generation, No space & traffic calculation and No email alerts

[Gosain]

Plesk Version: 9.3.0 Windows
OS: Windows Server 2008
Architecture: x64

Facing following problems:

1) No traffic calculation for Domains,Resellers,Clients.
2) Visit logs are being generated but No webstat is being generated.
3) No email alerts are being send out for the expiration, excess usage etc.

While trying to find the cause, when tried Daily Scheduled task run directly via command window, it gives the following error:

Fatal error: Call to undefined function plesk_get_ips() in C:\Program Files (x86)\Parallels\Plesk\admin\plib\ExtendedServerInfo.php on line 1663

Most probably because of above error the scheduled maintenance tasks are not being executed.

Any solution to this problem?

Thanks.