How do you set the DefaultButtonId when using the PredefinedButtons like in the code below?

using (NTaskDialog dlg = new NTaskDialog())

{

dlg.PredefinedButtons = TaskDialogButtons.Yes | TaskDialogButtons.No;

dlg.DefaultButtonId = (int)TaskDialogButtons.No; // ??? doesn't work ???

dlg.Title = "title";

dlg.Content.Image = NSystemImages.Warning;

dlg.Content.ImageSize = new NSize(32, 32);

dlg.Content.Text = "msg";

rc = (DialogResult)dlg.Show(this);

}