GetHistory-Returns-null-for-TDA-index-symbols-Solved

CODE:
         BarHistory vix1 = GetHistory(bars, "$VIX.X", "Balanced");
         vix = vix1.Close;

CODE:
using WealthLab.Backtest;
using System;
using WealthLab.Core;
using WealthLab.Indicators;
using WealthLab.ChartWPF;
using System.Drawing;
using System.Collections.Generic;

namespace WealthScript123
{
   public class MyStrategy : UserStrategyBase
   {
      //plot a market benchmark in its own pane and don't trade unless the benchmark is above its 50-day SMA
      public override void Initialize(BarHistory bars)
      {
         _spy = GetHistory(bars, "$VIX3M.X", "Balanced");
         PlotBarHistory(_spy, "SPYPane", WLColor.Silver);
         _smaSpy = SMA.Series(_spy.Close, 50);
         PlotIndicator(_smaSpy, default, default, default, "SPYPane");

      }

      public override void Execute(BarHistory bars, int idx)
      {
         if (!HasOpenPosition(bars, PositionType.Long))
         {
            if (_spy.Close[idx] > _smaSpy[idx])
            {
               //code your buy conditions here
            }
         }
         else
         {
            //code your sell conditions here
         }
      }

      BarHistory _spy;
      SMA _smaSpy;
   }
}