My guess is the TV only supports DLNA to retrieve media files?
If so, you need to enable DLNA on the DNS-320L.
Login to your DNS-320L, then go to Management->Application Management->Multimedia Services
Under Multimedia Shares Settings->Add.. Select the folder/s you want to share. The DNS-320L will now Index all the media files found in the selected folders. This may take quite a while, depending on the library size.
When it's finished indexing enable the server under UPnP AV Server Settings.
Now try again on your TV and it should find the DNS-320L DLNA server and you should be able to browse the library. Which media files you will see and which you won't see, depends on your TV and what filetypes it supports.