Share sticker on Viber.But sticker background turns black

I can use the code below to send the sticker to Viber. But after the background of the sticker turns black. My sticker is transparent. Please help me.

Link to a short image of my screen

     Here is my source code:

 Intent sharingIntent = new Intent(android.content.Intent.ACTION_SEND);
 sharingIntent.setType("image/png");

 sharingIntent.putExtra(Intent.EXTRA_STREAM, Uri.parse("file:///sdcard/sticker_demo/"   +transparentstickerpath));              
   startActivity(Intent.createChooser(sharingIntent, "Share via"));