crossing points

Hi,

I am developing my first robots from samples and having troubles that i can not explain.

The robot to create close the existing position and create a new position when slow period moving avarage crosses fast period moving avarage and when GrossProfit < anumber. But when I do the backtest and realtime testing it does not create marketorders or close positions at right positions ( crossing points). The GrossProfit condition works right. I have tried to find the error but I could not find it. Could someone please help me?. The codes as below

 protected override void OnTick()

        {

            if (Trade.IsExecuting) return;

            int lastIndex = slowMa.Result.Count - 1;

            int prevIndex = slowMa.Result.Count - 2;

            double currentSlowMa = slowMa.Result[lastIndex];

            double currentFastMa = fastMa.Result[lastIndex];

            double previousSlowMa = slowMa.Result[prevIndex];

            double previousFastMa = fastMa.Result[prevIndex];

            bool isLongPositionOpen = position != null && position.TradeType == TradeType.Buy;

            bool isShortPositionOpen = position != null && position.TradeType == TradeType.Sell;

            if ((previousSlowMa > previousFastMa) && (currentSlowMa <= currentFastMa) && !isLongPositionOpen) 

            {               

                ClosePosition();

                Buy();                

            }

            if ((previousSlowMa < previousFastMa) && (currentSlowMa >= currentFastMa) && !isShortPositionOpen)

            {               

                ClosePosition();

                Sell();               

            }

            if (position != null && position.GrossProfit < -StopLoss)

            {

               ClosePosition();

            }  

        }

        private void ClosePosition()

        {

            if (position != null)

            {

                Trade.Close(position);

                position = null;

            }

        }

        private void Buy()

        {

            Trade.CreateBuyMarketOrder(Symbol, Volume);

        }

        private void Sell()

        {

            Trade.CreateSellMarketOrder(Symbol, Volume);

        }

        protected override void OnPositionOpened(Position openedPosition)

        {

            position = openedPosition;

        }

    }

}