Why is this setter method in the Node class not working?

Question

I am trying to build kinda dynamic array. When trying to assign the array's last space the ignite property's set method creates a node and assigns this node's next reference. That's what I am thinking.

But this set method not even working and I am getting an IndexOutOfRangeException error. What is the problem? Is it possible?

CODE IN THE LINK

(My English is not good - sorry for this)

public class DynamicArray
{
    public static int index = 0;
    public Node head;
    public static Node last;
    
    public DynamicArray()
    {
        head = new Node();
    }

    public class Node
    {
        public object[] datas = new object[10];
        private object ignite = new object();
        public Node? next;

        public object Ignite 
        {   
            get 
            { 
                return ignite; 
            }
            set 
            {
                next = new Node();
                ignite = value;
            }
        }

        public Node()
        {
            datas[9] = Ignite;
            last = this;
            index = 0;
        }
    }

    public void Add(object data)
    {
        last.datas[index] = data;
        index++;
    }
}