How to get the horizontalLine's Y value?

I want to get the Y value when i put a  horizontalLine on a chart manually.

I tried the following things in the indicator：

        protected override void Initialize()
        {
            Chart.ObjectsAdded += Chart_ObjectsAdded;
        }

        private void Chart_ObjectsAdded(ChartObjectsAddedEventArgs obj)
        {
             Print("{0} objects added to chart", obj.ChartObjects.Count);
             var objtype = obj.ChartObjects.GetType();
             var newobj= obj.ChartObjects;
             Print(newobj.Last().Name);           // horizontalLine number
             Print(newobj.Last().ToString());     // cTrader.Automate.Adapters.ChartApi.ChartObjects.ChartHorizontalLineAdapter
             Print(newobj.Last().Comment);
             Print(newobj.Last().GetType());    // cTrader.Automate.Adapters.ChartApi.ChartObjects.ChartHorizontalLineAdapter
       }

Then, i get the correct name and Comment(nothing)，but can't get the Y value.

How to access the chart objects's value  like lines(horizontalLine's Y, vertical line's datetime) or rectangle(time and Y)?

Need help, thanks.