Video can not start after clicking the play button after stop button.

Help me.......
This is My Code..................................
button = FindViewById(Resource.Id.btnplay);
button.Click += Button_Click;

        button1 = FindViewById<Button>(Resource.Id.btnstop);
        button1.Click += Button1_Click;
    }

    private void Button1_Click(object sender, System.EventArgs e)
    {
        var videoView = FindViewById<VideoView>(Resource.Id.SampleVideoView);
        videoView.StopPlayback();
    }

    private void Button_Click(object sender, System.EventArgs e)
    {
        var videoView = FindViewById<VideoView>(Resource.Id.SampleVideoView);
        videoView.Start();


    }