duplicate job on USB device not work

Hi,

I have windows 2008 R2 server and backup exec 2014 SP2 (ver. 14.1 rev 1786, 64bit).

I have a deduplicate storage for backup FULL and Incremental.

I have configurated a dublicate jobs for all backup FULL on a 2 external USB disk.

I have configurated a storage pool 'external disk' whit external USB member and configurated in storage to duplicate job.

The duplicate job run after source task complete.

The problem:

The job run but not write (job status is Active:running but not write data in USB device).

I have delete and recreate job and storage but not works.

help me

thanks