Apple TV not talking to drobo

i have a share set up called Media on my Drobo, i cannot seem to get my apple tv 1 to talk to it properly. Please can you help. it shows my drobo in the network setup of nito tv but when i try and manually set up a share i get nowhere. please accept my apologies, im not an expert user. however i did manage to get my old USB drives working after some trial and error (since replaced with the drobo). please tell me what settings i should put into nito. Why isnt this as simpe as it is on my mac? on there im just asked for my username and password and its done.