Window Standard Edition server 2003 NT Backup Error 8019

Has anyone experience this issue below? my backup keep on getting this error on all weekly backups tapes on one server 2003 only . I'm using NT backup exec with Hp Dat72 drive tapes are 4mm DDS 36/72. any help would be greartly appreicated

Backup Status
Operation: Backup
Active backup destination: 4mm DDS
Media name: "Wednesdays"

Volume shadow copy creation: Attempt 1.
Backup (via shadow copy) of "C: NOS"
Backup set #1 on media #1
Backup description: "Wednesdays"
Media name: "Wednesdays"

Backup Type: Normal

Backup started on 7/16/2008 at 10:32 PM.
Backup completed on 7/16/2008 at 10:51 PM.
Directories: 2783
Files: 33587
Bytes: 4,394,875,056
Time: 18 minutes and 32 seconds
Backup (via shadow copy) of "D: DATA"
Backup set #2 on media #1
Backup description: "Wednesdays"
Media name: "Wednesdays"

Backup Type: Normal

Backup started on 7/16/2008 at 10:51 PM.
The requested media failed to mount. The operation was aborted.
The operation was ended.
Backup completed on 7/17/2008 at 1:54 AM.
Directories: 6524
Files: 70070
Bytes: 38,435,231,254
Time: 3 hours, 3 minutes, and 51 seconds

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