Make sure you have done the following when configuring Backup Exec on DSS.

Veritas:
Here you need to provide an IP address of a server running the Backup Exec. The "Directory Pass" is a password that the Backup Exec might prompt for.

Backup:

1. In Veritas Backup Exec set a user in the menu Network-> Logon Account Management,
2. Next enter the password such as earlier provided in the NAS Server function "Backup client setting",
3. By choosing "Backup" a "Backup Job Properties" window will appear,
4. A list of network shares will be shown in that window,
5. By clicking on the "Remote Selections" branch, and next on "Unix Agents", a NAS server name will appear,
6. After clicking the server "NAS_server/logical volume", a window "Logon Account Selection" will be displayed, #where you need to choose the same user name as in the point "1",
7. After choosing a user, the "Logical Volume" and NAS server shares will appear. By selecting the correct share and clicking the "Run Now" button, selected shares will be backed-up.

Note
In some settings, the window "Logon Account Selection" will not appear automatically. In this case you must right mouse click on the name "NAS_Server/share_volume", and then in the context menu choose "Connect As...". Only then the "Logon Account Selection" window will appear.