It lloks as if you want to backup NDMP data to a non-NDMP device.

In this case you must use DSA to do that.

From the book:

"In this scenario, the NetWorker software writes NDMP data to non-NDMP devices, including tape, virtual tape, AFTD, and

Data Domain devices. NDMP-DSA backups are more flexible than backups to NDMP devices, because NDMP devices must be physical or virtual tape."

Please have a look at the "Network Data Management Protocol User Guide" to start with.