Signal-does-not-open-a-position-for-negative-prices

CODE:

using WealthLab.Backtest;
using System;
using WealthLab.Core;
using WealthLab.Indicators;
using System.Drawing;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Text;

namespace WealthScript1
{
    public class Qs : UserStrategyBase
    {
      static List<BarHistory> Buys = new List<BarHistory>();
      double StdVal;
      int idx;
      TimeSeries _Std;
      SMA _rSMA;
      private TimeSeries opL;
   
        //create indicators and other objects here, this is executed prior to the main trading loop
        public override void Initialize(BarHistory bars)
      {
         StartIndex = 100;
         _rSMA = new SMA(bars.Close, StartIndex);
         bars.Cache["_rSMA"] = _rSMA;
         opL = new TimeSeries(bars.DateTimes);
        }

        public override void PreExecute(DateTime dt, List<BarHistory> participants)
        {
         foreach (BarHistory bh in participants)
         {
            _Std = (SMA)bh.Cache["_rSMA"];
            idx = GetCurrentIndex(bh);
            StdVal = _Std[idx];
            bh.UserData = Math.Round(StdVal, 3);
         }
         participants.Sort((a, b) => a.UserDataAsDouble.CompareTo(b.UserDataAsDouble)); //Lowest --> Highest

         Buys.Clear();
         for (int n = 0; n <= participants.Count - 1; n++)
         {
            if (Buys.Count == 10) break;
            if ((participants[n].UserDataAsDouble).ToString() != "NaN")
               Buys.Add(participants[n]);
         }

         FileStream fs = new FileStream(@"C:\Users\Administrator\Desktop\WL7_out\QS\WL7_" + dt.ToString("yyyyMMdd") + ".txt", FileMode.Create);
         StreamWriter sw = new StreamWriter(fs);
         sw.Write(" In Buy = ");
         foreach (BarHistory _strB in Buys)
         {
            sw.Write("," + _strB.Symbol);
         }
         sw.Flush();
         sw.Close();
         fs.Close();
        }

        //execute the strategy rules here, this is executed once for each bar in the backtest history
        public override void Execute(BarHistory bars, int idx)
        {
         bool inBuyList = Buys.Contains(bars);
         var BuyListPctEquity = CurrentEquity * 0.05 / bars.Close[idx - 1];
         opL[idx] = OpenPositionsAllSymbols.Where(t => t.EntryTransactionType.ToString() == "Buy").Count();
         opL[idx] += Backtester.Orders.Where(l => l.PositionType == PositionType.Long && l.IsEntry).Count();

         FileStream fs = new FileStream(@"C:\Users\Administrator\Desktop\WL7_out\QS\P\WL7_Position_" + bars.GetDate(idx).ToString("yyyyMMdd") + ".txt", FileMode.Create);
         StreamWriter sw = new StreamWriter(fs);
         List<Position> positions = GetPositionsAllSymbols(true);
         sw.Write(" Open = ");
         foreach (Position pos in positions)
         {
            if (pos.PositionType.ToString() == "Long")
               sw.Write("," + pos.Symbol);
         }
         sw.Flush();
         sw.Close();
         fs.Close();
         
         if (inBuyList && opL[idx] <= 19)
         {
            if (!HasOpenPosition(bars, PositionType.Long))
            {
               PlaceTrade(bars, TransactionType.Buy, OrderType.Market).Quantity = BuyListPctEquity;
            }
         }
         else if(!inBuyList)
         {
            if (HasOpenPosition(bars, PositionType.Long))
               ClosePosition(LastPosition, OrderType.Market);
         }
        }
    }
}