McGinleyDynamic-exception

When I use

CODE:
         int Length4 =  Parameters[9].AsInt;
         TimeSeries mcg = McGinleyDynamic.Series(bars.Close, Length4, true);

the code runs correctly, but when I use

CODE:
         int Length4 =  Parameters[9].AsInt;
         TimeSeries mcg = McGinleyDynamic.Series(bars.Close, Length4, false);

I get the following errors
Initialize Exception (A) Line 82 - Object reference not set to an instance of an object.
Initialize Exception (DTE) Line 82 - Object reference not set to an instance of an object.
Initialize Exception (AVGO) Line 82 - Object reference not set to an instance of an object.
Initialize Exception (CAH) Line 82 - Object reference not set to an instance of an object.
at WealthLab.PowerPack.McGinleyDynamic.Populate()
at WealthLab.PowerPack.McGinleyDynamic.Series(TimeSeries source, Int32 period, Boolean useSimplifiedFormula)
at WealthScript2.MyStrategy.Initialize(BarHistory bars) in :line 82
at WealthLab.Backtest.UserStrategyExecutor.ValidateError(List`1 symbols)