MarketSeries and class

Hi everyone,
I have created a class ...
Inside that class, the constructor uses data from Parameters and MarketSeries.
The class is called inside my indicator and at this point all works perfectly.

I decided to clean my code, and instead of passing Parameters several times for each methods and sub methods, i thought it may have been better to use Parameters as a global variable inside the calss.
So i created a new private field for the Parameter... so far so good, i can call the parameter everywhere in the class , no need to pass it as argument in every methods.

BUT ...

I tried to do the same thing with MarketSeries (as it's everywhere in my methods) but it doesn't work.
It builds successfully but the indicator draws nothing and in the log i have this error message:
"Crashed in calculate with nullReferenceException: Object reference not set to an instance of an object."

Is it possible to pass  MarketSeries as a variable that can be used by methods ? or do i have to pass it as argument in every method (as i did before)?
What is the most 'elegant' way to do it ?

This works:

//...
	public class MyAmazingClass
	{
		//Fields-------------------------
		public int Var1;
		public double I_Did_something;
		
		private int Parameter1;
		
		//Constructor---------------------
		public MyAmazingClass(MarketSeries marketSeries, int var1, int parameter1)
		{
			Var1 = var1;		
			Parameter1 = parameter1;
			
			I_Did_something = Do_Something(var1, marketSeries);
		}
		
		//Methods--------------------------
		private double Do_Something(int var1, MarketSeries MarketSeries)
		{
			var result = Parameter1 + MarketSeries.Low[var1]
			return result;
		}
	}
//...

This doesn't work :

//...
	public class MyAmazingClass
	{
		//Fields-------------------------
		public int Var1;
		public double I_Did_something;
		
		private int Parameter1;
		private MarketSeries marketSeries;
		
		//Constructor---------------------
		public MyAmazingClass(MarketSeries ms, int var1, int parameter1)
		{
			Var1 = var1;		
			Parameter1 = parameter1;
			marketSeries = ms;
			
			I_Did_something = Do_Something(var1);
		}
		
		//Methods--------------------------
		private double Do_Something(int var1)
		{
			var result = Parameter1 + marketSeries.Low[var1]
			return result;
		}
	}
//...

...in both cases, the class is called from Calculate:

//...
	public override void Calculate(int index)
	{
		//...
		amazing_object = new MyAmazingClass(MarketSeries, index, parameter1);
		//...
	}
//...

I just have few weeks of experience using c# and i may not have used the right words to explain the problem... anyway i hope this question makes sense ...