cant find my computer in apple tv

Trying to set up my apple tv mirroring but my mac doesn't even detect the apple tv. When using apple tv I can see and browse my photos in photo stream but nothing else works. I turn on home sharing on the apple tv but then when i go to computers it doesn't come up. It tells me to turn on home sharing in itunes which it is but still nothing. i've already tried going into system preferences and displays to turn activate the apple tv but it says no devices detected?!?!!?! everything is updated...the apple tv software, itunes, etc. Anyone have a solution?