airplay mirror with Macbook air in living room, wants to connect to the apple tv in the bedroom (a separate room) I can see picture on tv in the livingroom but no sound

I have 2 apple tv devices one in the living room one in the bedroom. when I am in the living room and try to airplay mirror my macbook air to the apple tv the I have the option to connect to either one, but when I click apple tv living room, the check mark automatically checks next to the apple tv bedroom. I get picture in the living room but no sound. both are connected to the same wifi network. the one in the bedroom we have had for 2 days the one in the living room we have had for 9 months. this is frustrating as we only use apple tv and airplay mirroring we do not have cable. thank you