Sharepoint bkp to tape

Hi all,

I have a policie in NBU 7.5.0.6 to backup my Sharepoint, it only run if I make backup to disk storage unit, when I change to tape storage unit it shows me this message and finished with status 71.

"none of the files in the files list exist (71)

Master server NBU7.5.0.6 with OS windows 2008 R2

Sharepoint front end server and SQL server NBU client 7.5.0.6 with OS windows 2012 R2

Can anybody help me?

Thanks