Command line restore of DAR files

Hi

We have a NAS326 running RAID1 and a backup to a USB HDD.  I want to be able to prove to mself that in the event of the NAS box dying I can restore the backup files using something other than the NAS box's own restore tool.

So I've downloaded DAR.exe from sourceforge and tried:

DAR -l "E:\Backup Job 1\F-1540977945.31.dar"

Which should just check the contents

But all I get is:

No backup file is present in file:///dar64-2.5.17-win64 for archive E:\Backup Job 1\F-1540977945.31.dar, please provide the last file of the set

.31.dar is the last file.  But I get the same with .1.dar and the .lst.dar file

The archive is not encrypted or compressed.  Can anyone help??