Why "HasCrossedAbove/Bellow" didn't returned true for this picture.

Hello there and thanks in advance.

I have been trying to find and explanation for HasCrossedAbove/Below not returning true for this picture.

The black curve (_ma1) is my main moving average: Time Series, closed, 15 periods.

The blue curve (_ma2) is my second moving averafe: Triangular, closed, 15 periods.

I made a simple trend bot for placing a long position when _ma1 crosses above _ma2 and a short position when _ma1 crosses below _ma2. Such crossings also close the any opposite positions.

My bot parameters match the ones used on the above picture: EURUSD m15.

My code for handling positions is given as such:

protected override void OnBar()
        {
            // Result.Last(0) is far more profitable than Result in backtesting.
            if (_ma1.Result.HasCrossedAbove(_ma2.Result.Last(0), 0))
            {
                ClosePositions(TradeType.Sell);
                OpenPosition(TradeType.Buy);
            }

            if (_ma1.Result.HasCrossedBelow(_ma2.Result.Last(0), 0))
            {
                ClosePositions(TradeType.Buy);
                OpenPosition(TradeType.Sell);
            }
        }

        private double _volume
        {
            get
            {
                return Symbol.NormalizeVolumeInUnits(Quantity * Account.FreeMargin * Account.PreciseLeverage / 100);
            }
        }

        public void ClosePositions(TradeType tradeType)
        {
            foreach (Position position in Positions.FindAll(_label, Symbol, tradeType))
                ClosePosition(position);
        }

        public void OpenPosition(TradeType tradeType)
        {
            if (Positions.FindAll(_label, Symbol, tradeType).Length != 0)
                return;

            double? sl = GetStopLoss();

            ExecuteMarketOrder(tradeType, Symbol, _volume, _label, sl, null, null);
        }

        public double? GetStopLoss()
        {
            if (SL != 0)
                return SL;
            else
                return null;
        }
    }

I have read this page https://ctrader.com/api/reference/functions/hascrossedabove. It kind of touches the question, but no entirely.

Again, thanks.