Sheduled Backup with Win 2000 Server

I’m trying to schedule a backup using a batch file in Windows 2000 Server. I’ve created the batch file and it runs fine when I double click it or call it from the command prompt. The trouble is I’m trying to run it as a schedule using “Scheduled Tasks” nothing happens. I’ve also tried running NTBACKUP and creating a scheduled task from there but the same thing happens – in fact I can’t get anything to run from the scheduler program. I’ve just installed 2000 Server from scratch as a PDC and installed Service Pack 2. I’ve also tried using different users to run the job but no difference. What am I doing wrong???