Backup Exec 2010 Transfer Rate very slow after changing to LTO4 drive

Hello,

we are using the following System:

Windows Server 2008 r2 64bit, Tandberg LTO4 SCSI drive (driver Version 1.0.7.0),  SCSI Adapter LSI Ultra320 2000 series

Backup Exec 2010 Version 13.0 Rev. 2896

After changing our old drive (Tandberg LTO2 SCSI drive) to the LTO4 drive our Transfer Rate of the Backup drops from 1250 MB/s to 150 MB/s.

The Transfer Rate of the LTO4 Drive should be aroung 5000 MB/s.

We reinstall the Tape Driver in Backup Exec, we tried a Backup without compression, but still the Transfer rate is very slow.

Because we can't create a full Backup, I reinstall the old drive and everything is working fine again.

Please give us some hints.

Kind Regards

Frank