Shell Sort in C#. Variable will not set as divided value.

Hello,

I am programming a ShellSort in C#.  I am having trouble with assigning a variable called 'gap' and I can't for the life of me understand why it will not come out with the correct value.

If I hover over the piece of problem code, it shows that the outcome of the calculation is '5', but then the variable always seems to have the value 0.

Thanks for any assistance, I've included my code in the code section and I've pointed out the problem code.

Thanks for any help,

Luke

// Code by Luke Coulton 29.03.2011
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ShellSortConsole
{
    class Program
    {
        // Method for the  Shell Sort algorithm
        static List<int> ShellSort(List<int> Data)
        {
            int numberCount = Convert.ToInt32(Data.Count);
            

            //
            // This won't divide properly!!  Always giving value '0'
            // \/ \/ \/ \/ \/ \/ \/
            //
            int gap = numberCount / 2;

            // Do-while loop for whilst gap is more than zero
            do
            {
                for (int i = (gap + 1); i <= Data.Count; i++)
                {
                    // Create the new pointer value
                    int pointer = i - gap;

                    do
                    {

                        if (Data[pointer] > Data[pointer + gap])
                        {
                            int temp = Data[pointer];
                            Data[pointer] = Data[pointer + gap];
                            Data[pointer + gap] = temp;

                            // Set the new pointer value
                            pointer = pointer - gap;
                        }
                        else
                        {
                            pointer = 0;
                        }

                    } while (pointer > 0);

                    gap = gap / 2;
                }

            } while (gap > 0);

            return Data;
        }

        static void Main(string[] args)
        {

            // List of values to sort
            List<int> sortingValues = new List<int> { 500, 300, 200, 400, 100, 500,300,200,400,100 };

            // Invoke the method
            List<int> numberz = ShellSort(sortingValues);

            foreach (int sortedValue in numberz)
	        {
                Console.Write(sortedValue + " ");
            }

            // ReadLine to prevent closure of console
            Console.ReadLine();

        }
    }
}

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