chart's higher y label values can't be updated

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C#

WPF

WinForms

chart

I've used windows form chart to create a chart dynamically but I've this problem; when x value goes to higher values the y label values can't be updated.

I create the chart with this function:

func(){
        _counter++;
            Dispatcher.Invoke(new Action(()=>{
                series.Points.Add(100 * Math.Sin((.0002 * _counter)));
                if (_counter > 1000)
                {
                    series.Points.RemoveAt(0);
                    chart1.Invalidate();
                }
            }));
}

this code is called 10000 times. when I start removing points from the start of the chart the y label value remains on 0 to 20 , but function values for x>1000 are more than 20 so nothing is shown. how can I fix it?