NetBackup Server with Enterprise Disk should be OK. (I think?)
Have you followed the procedure to create a storage server? It's in the admin guide vol. 1 ("Creating an AdvancedDisk storage server") and also in this TechNote:
DOCUMENTATION: How to create an Advanced Disk disk pool using a media server and its file systems.
http://support.veritas.com/docs/302540
For you, everywhere it says "media server" - that's your master. (You probably knew that already.)
This instructions hopefully match up with your version and operating system, which you didn't provide in your original post. :( If not, you might want to open a support case with us and confirm the Server + Enterprise Disk combo.