Cannot connect airplay from new computer to tv

My other apple devices connect to our tv via airplay. I just got a new MacBook Air and cannot connect it. When I open the airplay icon on the top right hand side, it shows in gray that it is looking for Apple TV and then "off". There is no other choice except display preferences. I only have one network at home, which both tv and new computer are on. I have opened the bluetooth icon and can watch the computer search. Again, my other MacBook Air and phones can connect right now, but not the newest computer.