Call screen black screen on receive call

[lohnsonok]

AgoraRtcEngine.onUserJoined = (int uid, int elapsed) { setState(() { hasUserJoined = true; final info = 'onUserJoined: $uid'; _infoStrings.add(info); _users.add(uid); }); };

I don't understand how uid is getting on press take call button. It appears call is not visible(black screen) how to solve this please

Note : I'm using agora in testing mode