[Major] [90:51] Cannot write to device (Details unknown.) (Windows)

Hey there,

we have some trouble with an windows backup on our DP 9.02 environment.

Backup device is an VTL.

The Server we want to backup is an Winodws 2012 Server. The size of the files should be ~ 2 TB, so the backup need some time. For example:

Start: 03:00:07

Error: 13:33:03

Until the error everything looks fine. But then:

Major] From: BMA@backup_gateway.test.com "VTL_WIN_DEV01"  Time: 22.05.2015 13:33:03
[90:51]      /dev/nst28
    Cannot write to device (Details unknown.)

[Critical] From: VBDA@windows_server "I: [Data1]"  Time: 22.05.2015 13:33:05
    Received ABORT request from SM => aborting.

[Critical] From: VBDA@windows_server "J: [Data2]"  Time: 22.05.2015 13:33:05
    Received ABORT request from SM => aborting.

[Critical] From: VBDA@windows_server "G: [Home1]"  Time: 22.05.2015 13:33:05
    Received ABORT request from SM => aborting.

[Critical] From: VBDA@windows_server"I: [Data1]"  Time: 22.05.2015 13:33:05
    Connection to Media Agent broken => aborting.

[Critical] From: VBDA@windows_server "J: [Data2]"  Time: 22.05.2015 13:33:05
    Connection to Media Agent broken => aborting.

[Critical] From: VBDA@windows_server "G: [Home1]"  Time: 22.05.2015 13:33:05
    Connection to Media Agent broken => aborting.

First i thought it could be an timeout or something, but the start and error time doesent indicate that.

Do you have an ideas?