My Iphone apps will cast to my Apple TV, but my laptop and other programs will not?

I have an Apple TV in my office, and when I use Netflix, AmazonPrime, Hulu etc on my phone the "cast" button appears and I can cast.

However, my laptop will not find any cast destinations. Also, I downloaded a few CAST apps on my iphone to try and cast browser pages and they don't find any destinations either.

Added (1). My Iphone apps will cast to my Apple TV, but my laptop and other programs will not? (there's no chromecast plugged in)

For the record its called the AirPlay button, not the cast button.

You didn't state what laptop it is you have so I'll just have to assume that it is not capable of AirPlay.

Also the Apple TV & Google Chromecast are 2 similar but separate devices that have their own methods of connectivity.