ntbackup issue using /p flag on Server 03 with an LTO Ultrium 3 drive

I have created some batch scripts which run as scheduled tasks on one of our

servers. There are 2 scripts for each day, one of which backs up to a file

for the onsite backup, the other of which backs up to the server's tape

drive for the offsite backup.

The onsite backup script works fine, using the following command:

c:\windows\system32\ntbackup.exe backup "@C:\Backup Scripts\onsite.bks" /n

"Tuesday morpork onsite set created %morporkdate% at %morporktime%" /d

"Tuesday morpork onsite set created %morporkdate% at %morporktime%" /v:yes

/r:no /rs:no /hc:off /m normal /j "Tuesday morpork onsite" /l:s /f

"M:\Tuesday.bkf"

where %morporkdate% and %morporktime% are variables created earlier in the

batch file. The onsite.bks file reads as:

C:\Backup Scripts\

D:\CleanupScannedDocuments\

E:\SharedData\

SystemState

The offsite backup on the other hand does not work for some reason. The

command being executed is:

c:\windows\system32\ntbackup.exe backup "@C:\Backup Scripts\offsite.bks" /n

"Wednesday morpork offsite set created %morporkdate% at %morporktime%" /d

"Wednesday morpork offsite set created %morporkdate% at %morporktime%"

/v:yes /r:no /rs:no /hc:off /m normal /j "Wednesday morpork offsite" /l:s /p

"Wednesday morpork"

and the offsite.bks file reads as:

C:\Backup Scripts\

D:\CleanupScannedDocuments\

E:\SharedData\

SystemState

..

The tapes will hold 400GB native/800GB compressed (being optimistic), we are

currently backing up around 50GB as it is a new server. When I perform a

manual backup to the tape it works fine. When I run the command above

though, the tape activity LED flashes for a few seconds before stopping.

Can anyone recommend what I am doing wrong? I'm pretty sure it's down to me

not using the /p flag correctly, but I've not found any helpful

documentation on what arguements to give to this parameter. In one example I

found online, the value was a seemingly abstract string.

If anyone is able to suggest something I would be very grateful.