C# ColorLine not showing up in TChart

Question

I currently have an TChart where I want to introduce a draggable horizontal line which changes the color of the points below the line. I have chosen to use ColorLine for this purpose but the line does not appear in the TChart. Am I using the right TChart tool for the job or am I missing something?

Below is the stripped down version of my current code.

public class testClass
{
    private ColorLine line;
    private double lineYVal = 5;
    private TChart savedChart;

    public testClass()
    {
        line = new Colorline();
        line.AllowDrag = true;
        line.Pen.Color = Color.Red;
        line.EndDragLine += lineDragHandler;
    }

    public void foo(TChart chart)          //chart is prepopulated with datapoints from 0->10
    {
        savedChart = chart;
        //existing code which assigns colors
        chart.Series[0].ColorRange(chart.Series[0].YValues, double.MinValue, lineYVal, Color.Red);
        chart.Series[0].ColorRange(chart.Series[0].YValues, lineYVal, double.MaxValue, Color.Blue);

        //my attempt to add a line
        chart.Tools.Add(line);
        line.Active = true;
        line.Axis = chart.Axes.Left;
        line.Value = lineYVal;
    }

    private void lineDragHandler(object sender)
    {
        lineYVal = line.Value;
        savedChart.Tools.Clear();     //remove existing line from chart
        foo(savedChart);              //redo colors and re-add line
    }
}

Answer 1

It turns out that while the line was being added correctly, the code I was using to display the chart was not updating the chart properly and was displaying a version of the chart from before it was passed into my highlight function.