Robot chart drawing

Hi I'm pretty new to CAlgo forgive me if im being really stupid. Is it the case that robots cannot draw on charts?

I'm trying to draw a blue down arrow at the last bar, however its not drawn to the chart.

Should be simple enough but I cant figure out.

 protected override void OnBar()
 {
    var lastBar = Bars.LastBar;
    Chart.DrawIcon(lastBar.OpenTime.ToString(), ChartIconType.DownArrow, lastBar.OpenTime, lastBar.High, Color.Blue);
 }