Woohoo! I just figured out, after many hours of searching the Internet, why my D-Link 323 wasn't showing in ITunes as a Shared device.
Do not select "Root" in the itunes SERVER configuration page.
I had to point directly to my music folder "called MP3" in Volume_1 and it popped up right away.
(Volume_1/Shared Data/Music/MP3)
I had also tried "Shared Data" but it didn't work. Maybe it didn't like the other type of file/extension.

Hope it fixes your problems too.