Using Unity Ads with Android

I am building a game for Android and am using Unity Pro. I’m using Unity Ads directly out of the asset store and have followed the instructions in the documentation. I have used the provided example script that puts a button on the screen that will read “Waiting” until an ad is ready at which point it will read “Show Ad”. It then displays a blue screen when this button is pressed that says that everything is working. However when I build the game onto my tablet the button never changes from “Waiting” to “Show Ad”. I can’t figure out why an ad is never ready on Android but it is in the Editor.

Ditto, it works fine on phone. But advertisement is never ready on tablet running 4.4.2