MarketSeries not working properly

Hello, I made the following code to calculate the average pip variation between each close on all the graph of the selected custom timeframe (which may differ from the symbol one) but I'm having some weird bugs...

[Parameter("Timeframe to calculate graph's averages")]
        public TimeFrame mTimeframe { get; set; }


        // -------------------------------------------------- ON START --------------------------------------------------
        protected override void OnStart()
        {

            MarketSeries mathTimeframe = MarketData.GetSeries(mTimeframe);
            double graphVariationSum = 0;

            int count = 0;
            int marketSeriesCloseLength = MarketSeries.Close.Count;
            for (int i = marketSeriesCloseLength - 1; i >= 1; i--)
            {
                double currentClose = mathTimeframe.Close[i];
                double previousClose = mathTimeframe.Close[i - 1];

                if (currentClose > previousClose)
                    graphVariationSum += currentClose - previousClose;
                else if (currentClose < previousClose)
                    graphVariationSum += previousClose - currentClose;
                else
                    graphVariationSum += 0;

                count++;
            }

            double averageGraphVariationSum = graphVariationSum / count;


            Print("Last close = " + mathTimeframe.Close[marketSeriesCloseLength - 1]);
            Print("graph variation sum = " + To.Pips(graphVariationSum, Symbol.PipSize) + " average variation = " + To.Pips(averageGraphVariationSum, Symbol.PipSize));
        }

The first bug happens when I change the timeframe of the symbol, it makes the custom timeframe having a different result when it should always have the same result since it's one of the Parameters and does not change :

Symbol Timeframe = m1

Custom Timeframe = m1 (parameter name is mTimeframe)

Result of sum = 2830

Symbol Timeframe = h1

Custom Timeframe = m1 (parameter name is mTimeframe)

Result of sum = 45

As you can see the result changed but the custom timeframe didn't.

I can't understand why... It should stay the same because of the GetSeries : MarketData.GetSeries(mTimeframe).

My question is why does it change and how to make it calculate only on the custom selected timeframe ?

You can see the second bug on the first image.

The last close printed by the bot (mathTimeframe.Close[marketSeriesCloseLength - 1]) is not the same as the one shown on the graphic (1.13303 instead of 1.13063.).

The last bug happens when I set a custom Timeframe higher than the Timeframe of the symbol.

The value of the last close doesn't get displayed, instead I get a "Not numerical" message...

Thanks for your help.