Looks like you are not getting a good network ipaddress for you AppleTV. Do you have a router? Is the AppleTV connected to the Router? If so, can you AppleTV access the internet applications (like Movie Trailers). If that all works well then your AppleTv should be able to talk to the MAC. If still having problems go into the settings on the AppleTV looking for the Network. Do you have a ipaddress. Usually it would be something like 192.168.1.nnn.