Index-was-Out-Of-Range-error-on-a-DataSet-with-over-500-members

CODE:


public class MyStrategy : UserStrategyBase
    {
   public MyStrategy() : base()
        {

        }

        public override void Initialize(BarHistory bars)
        {
xSMA = new SMA(bars.Close,20);
Plot(xSMA,Color.FromArgb(255,0,0,0));
xADX = new ADX(bars,10);   *******Line 22******
Plot(xADX,Color.Green);
xDIPlus = new DIPlus(bars,10);
Plot(xDIPlus,Color.Blue);
xDIMinus = new DIMinus(bars,10);
Plot(xDIMinus,Color.Red);

StartIndex = 20;
        }

Initialize Exception (TF20210106.A) Line 22 - Index was out of range.Must be non-negative and less than the size of the collection.(Parameter 'index').
at Wealthlab.Indicators.DirectionalMovement..ctor(BarHistory bh, Int32 period)
at Wealthlab.Indicators.ADX.Populate()
at Wealthlab.Indicators.ADX..ctor(BarHistory bh, Int32 period)
at WealthScript7.MyStrategy.INITIALIZE(BarHistory bars) in :line 22
at WealthLab.Backtest.UserStrategyExecutor.PublishError(List`1 symbols)