How do I take a snapshot on android.

Hello. I am working on a game that allows you to take snapshots of it in-game. The only problem is that it doesn't work. When I press the button to download the png, it doesn't work. I am using Intel XDK so is there any plugins or permissions I should be using?

Thanks

P.S It works fine on the computer.

I have the same issue. Would be nice to see a solution )