Add Max Positions to code

Hi guys, Im backtesting this MA code, its working well for now, Im trying to improve it with max number of positions but it didnt work, anyone can help me?

using System;
using System.Linq;
using cAlgo.API;
using cAlgo.API.Indicators;
using cAlgo.API.Internals;
using cAlgo.Indicators;

namespace cAlgo
{
    [Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
    public class EMAcBot1 : Robot
    {

        [Parameter("Max No of Positions", DefaultValue = 100, MinValue = 1, MaxValue = 1000, Step = 1)]
        public int NoOfPositions { get; set; }
        
        [Parameter("Source")]
        public DataSeries Source { get; set; }

        [Parameter("Periods", DefaultValue = 14)]
        public int Periods { get; set; }

        [Parameter("Quantity (Lots)", DefaultValue = 1, MinValue = 0.01, Step = 0.01)]
        public double Quantity { get; set; }
        [Parameter("Stop Loss", DefaultValue = 10)]
        public int sl { get; set; }
        [Parameter("Take Profit", DefaultValue = 10)]
        public int tp { get; set; }
        private ExponentialMovingAverage ema;

        protected override void OnStart()
        {
            ema = Indicators.ExponentialMovingAverage(Source, Periods);
        }

        protected override void OnBar()
        {
            int index = MarketSeries.Close.Count - 1;
            if (ema.Result[index - 2] < MarketSeries.Close[index - 2] && ema.Result[index - 1] > MarketSeries.Close[index - 1])
            {

                Open(TradeType.Sell);
            }
            else if (ema.Result[index - 2] > MarketSeries.Close[index - 2] && ema.Result[index - 1] < MarketSeries.Close[index - 1])
            {

                Open(TradeType.Buy);
            }
        }

        private void Open(TradeType tradeType)
        {

            var volumeInUnits = Symbol.QuantityToVolume(Quantity);

            ExecuteMarketOrder(tradeType, Symbol, volumeInUnits, "EMA", sl, tp);
        }
    }
}