Windows 2000 Server Backup

I am trying to use the Windows 2000 server backup program to backup my server each night. I have a DLT tape drive in the machine. I use the backup wizard to create a backup job. I assign the job a media tape name, and just have it backup the entire server. Nothing complicated, but each morning I come back and the report for the backup says ” the backup could not be completed because there was not an unused media in the tape drive.” Can anyone help me setup this backup program so that it will run each night with the correct tape name?