Change tasks runtime using schtasks

[Guest Super Play]

I am attemtping to use schtasks to change a taks run time using the command

line tool "schtasks"

 

As a test I am attempting to change the time of the scheduled defrag, using

the syntax:

 

SCHTASKS /Change /TN ScheduledDefrag /ST 15:00

 

This returns the following error:

 

ERROR: The specified task name "ScheduledDefrag" does not exist in the

system.

 

However if I run "schtasks /query " to quey all taks the folllowing is

retured

 

Folder: \Microsoft\Windows\Defrag

TaskName Next Run Time Status

========================================== ====================

===============

ManualDefrag N/A Ready

ScheduledDefrag 09/01/2008 01:00:00 Ready

 

 

Even in the Vista Scheduled taks GUI it shows the tasks name as

"ScheduledDefrag"

 

 

What is going on?