airplay not working on new macbook pro and apple tv2
i have a new macbook pro and new apple tv device and have used them together easily. However, now I can't find the apple tv icon on the top bar and have searched everywhere for it, turning off and on the home sharing, restarting the apple tv. any other hints, or is it just something basic...I am new to apple products...
Thanks
MacBook Pro, iOS 6.1.3