Hi! I need help with my Apple TV!

I had just got my Apple TV and trying to use it, but I do not see Airplay icon on my iPad 2/iPhone 5S's control center (the one scroll up from ur middle bottom screen). I tried everything on apple forum like same wifi, on Airplay on Apple TV, nothing seems to work.

I am able to use Apple TV o watch youtube videos but the Airplay icon just dont come out. Last night, when my internet is down, strangely the Airplay icon appeared and I can mirror content to my Apple TV. But today the Airplay icon wouldn't come out again! Anyone know know to solve this problem?