Thread: Function from .cs file calling function from a different .cs file

What I am trying to do (in brief terms):
I have a function in a .cs file (A) that needs to access a function in a different .cs file (B). Based on certain calculations, (B) will alter (A) variables.

The problem:
I keep getting the following WARNINGs:
warning CS0649: Field 'programX.MainWindow.tCodes' is never assigned to, and will always have its default value null
warning CS0649: Field 'programX.TriggerCodes.function_MainWindow' is never assigned to, and will always have its default value null

Possibly needed details:
OS: Windows 7 64-bit
Compiler: MS Visual Studio 2010 Ultimate
Language: C# (WPF)
Framework: 4.0

And finally, a sample piece of code:

In "MainWindow.xaml.cs":

Code:

namespace programX
{
	public partial class MainWindow : Window
	{
		public TriggerCodes tCodes;
		
		public MainWindow()
		{
			InitializeComponent();
		}
		
		protected internal void doSomething()
		{
			if (tCodes.triggerCodeFound("Hello World"))
				return;
			
			Console.WriteLine("Didn't find it");
		}		
		
		public void sayHello(string message)
		{
			StringBuilder msg = new StringBuilder();
			msg.Append("Hello ");
			msg.Append(message);
			
			// *should* write "Hello Silly Person!"
			Console.WriteLine(msg.ToString());
		}
	}
}

In "TriggerCodes.cs":

Code:

namespace programX
{
	public partial class TriggerCodes
	{
		public MainWindow function_MainWindow;
		
		public bool triggerCodeFound(String theData)
		{
			if ((theData.IndexOf("World") > (-1)))
			{
				this.function_MainWindow.sayHello("Silly Person!");
				return (true);
			}
			return (false);
		}
	}
}

I am a C/C++ coder by trade, and just learning C#. In C/C++, this is a rather simple concept for me to grasp, however, C# is kicking my arse and laughing all the way.

Any help to avenge this temporary nemesis would be awesome.

Thanks!

In line 5 of your first block of code you create an instance variable tCodes. Where is the code that assigns an object to this instance variable?
In line 5 of your second block of code you create an instance variable function_MainWindow. Where is the code that assigns an object to this instance variable?

This is basic OO stuff, applies to C++, C#, etc.