Do you get the airplay icon near the clock on your mac or can you just airplay through itunes? If you don't have that icon I think you have a network issue.
As ever reboot router, ATV (take ALL cables out for 30 seconds) and MBA. You have followed advice, confirm you have checked same network and apple ID with homesharing on (should be good though if you get music).
Next check is that the cable and tv port are OK, do you have another BR device to play on the tv and another cable to try?
First steps to try,
Thanks for the quick response Jules!
Yes I have the AirPlay icon on my laptop menu bar. I was able to select AppleTV once the connection was senced. However my TV just goes to a blank black screen. I know it is connected because I was able to go onto youtube.com and my iTunes. and play something and hear the audio from my TV but not video has appeared yet.
I checked the cables and the cord and restared both my laptop, my router, and my appleTV and still I only get the blank screen when I connect the two. Oh! It also auto-disconnects after a certain amount of time.