Hello,
Usually, in most of the cases, the "" error is observed due to configuration settings of Overwrite protection and append periods or if there is no free space on the media. Sometimes, this error happens if data to be backed up exceeds the capacity of the tape.
Please have a look at the technote below:
An explanation of the "Overwrite Protection Period" and the "Append Period"
http://support.veritas.com/docs/237374
The basics of Advanced Device and Media Management for VERITAS Backup Exec (tm) for Windows Servers
http://support.veritas.com/docs/192265
Thanks,
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