C# IEnumerable, IEnumerator Reset Function Not Get Called

I'm basicly trying to make my class able to iterate using foreach. I read this tutorial. MSDN. It seems very straight forward. However, I have a problem when I want to iterate second time. I debugged it; and it turned out that it doesn't call the Reset() function.

Class A

class A : IEnumerable, IEnumerator
{
    int[] data = { 0, 1, 2, 3, 4 };

    int position = -1;

    public object Current
    {
        get
        {
            return data[position];
        }
    }

    public bool MoveNext()
    {
        position++;
        return (position < data.Length);
    }

    public void Reset()
    {
        position = -1;
    }

    public IEnumerator GetEnumerator()
    {
        return (IEnumerator)this;
    }
}

When I run the following main function; it never calls Reset() function. So, after one loop I never be able to iterate my class again.

Main

static void Main(string[] args)
{
    A a = new A();

    foreach (var item in a)
    {
        Console.WriteLine(item);
    }

    Console.WriteLine("--- First foreach finished. ---");

    foreach (var item in a)
    {
        Console.WriteLine(item);
    }
}

Output:

0
1
2
3
4
--- First foreach finished. ---
Press any key to continue . . .

Any thoughts?