List Problem

So I have function that simply is suppose to add stuff to it however when i test it after in the function im getting a null object?!?!?!? Please help!! from the log i get null then 121.

         public List<PathNode> NodeList;
         public int size;
         public GameObject Node;
         public void createNodeGrid()
         {
             for(int i=0;i<=2000;i+=200)
             {
                 for(int k=0;k<=2000;k+=200)
                 {
                     PathNode tmp;
                     tmp= Instantiate(Node, new Vector3(i, 20, k), Quaternion.identity) as PathNode;
                     NodeList.Add(tmp);
                     
                 }
             }
             Debug.Log(NodeList[0]);
             size = NodeList.Count;
             Debug.Log(size);
            
         }