Mounting shared folder on a Drobo external drive

Has anyone managed successfully to mount a shared folder that is located on an external Drobo drive that is connected to the main computer. I have been told by the support people that the volume path should be just the folder name but that doesn’t work. I get “cannot allocate memory” error. What I don’t understand how does the system know which drive the folder is on.

I am running Windows XP SP3, Apple TV s/w version 3.0.1 and aTV flash 4.0.6

Appreciate any advise.