Show Android device volume slider

Hi.

I’m using the Corona key function to change the volume of my app by the hardware buttons “volumeUp” and “volumeDown”. My function is alike the one at http://coronalabs.com/blog/2013/03/26/androidizing-your-mobile-app/ .

What I can’t understand is why the Android volume slider does not show up in the screen. Another thing I’ve realized is that other apps on my phone gets a higher volume than my app’s. In other words, the volume of the phone is set to the other apps, while it’s not done to mine.

Is there some way I can fix it or Corona simply can’t handle that?

Thank you.