Testing unity ads

I'm about to finish my first mobile game and upload it to PlayMarket. All I need is to makesure that unity ads works fine. I imported asset and made a button for reward video. It works fine in test mode on PC, but when I build my game to .apk and run it on mobile. The button just dead. It does nothing. Is it ok? Or something is wrong? Btw when I tried to build .apk file there was an error "1 exeption was raised by workers" so I deleted "plugins" folder from my project so I can build it normally.

 

I'm using Unity Ads SDK 3.0. I imported it from Asset Store with Package Manager. When I debug my device and pressing the reward ad button, there is no logs at all. But if I add "Debug.Log("Reward Video");" in the script where I play Ad. It debugs it in console when I press the button. But nothing else. There is no any ad playing, I'm not getting a reward for ad, and button not disappears. But In the test mode on PC, everything works just fine..

 

Ok I solved the problem! By importing back plugins folder and remove the checkmark on "Enable built-in Ads extention"