The first thing you go to do is to have it hooked up hardwarewise correctly. If you are connecting this DLT in daisy chain with your existing DLT, keep in mind about SCSI ID´s (different ID´s for each device). There is a maximum of two DLT 7000 tape drives per SCSI channel.
When you first start your server look for the SCSI Host adapter message telling you that the device has been detected and the appropiate ID is shown on the screen.
Then after the operating system is up, make sure that the OS has recognized the Host Adapter and all the drives attached to it (2 in your case). Please remember that the last scsi device in the daisy chain is the one that gets the terminator.
Arcserve IT 6.61 will recognize the device, just to make sure go to devices and look under the host adapter you should see both drives.
This should do it.
Good Luck
Carlos Alberto Cruz