need help with null reference

hi first time poster, kinda basic at programming lvl, im getting a:

NullReferenceException: Object reference not set to an instance of an object gridmaker.Start () (at Assets/scripts/gridmaker.js:55)

and i would be tankfull if anybody can help me find the bugger :)

both scripts are in the same game object: pathManager.js

 #pragma strict
 import System.Collections.Generic; //required for list functions
 
 var gridArray = new List.<Transform>(); 
 
 
 
 
 
 public function AdGridBlock(a : Transform){
 
     gridArray.Add(a);
     var _tempLenght = gridArray.Count;
     
     Debug.Log("added: " + a + "array lenght now: " + _tempLenght);
     
 }
 
 
 function Start () {
     
 }
 
 function Update () {
 
 }

and gridMaker.js

 #pragma strict
 // Instantiates a prefab into a grid
 
 // new grid name
 var gridName = "newGrid";
 
 // grid block prefab
 var prefab : GameObject;
 
 // defines _newObj as a GameObject 
 private var _newObj : GameObject;
 
 // create grid at this position
 var initPOSX = 0; //depth
 var initPOSY = 0; //with
 var initPOSZ = 0; //height
 
 var gridX = 5;
 var gridY = 5;
 var spacing = 2.0;
 
 //temp
 private var pathmanager : pathManager;
 private var tempName : Transform;
 
 
 function Start () {
 //
 // create and define our grid holding object
 //
     var _parent = new GameObject (gridName);
     _parent.layer = 9; //select path layer, remove for other purposes
     _parent.transform.position = Vector3(initPOSX, initPOSZ, initPOSY);
 //
 // create the grid and parent the objects to empty _parent object we just created,
 // the grid is created from _parent origin position and naming flows left to right then to the bottom
 //
     for (var x = 0; x < gridX; x++) {
         for (var y = 0; y < gridY; y++) {
             var pos = Vector3 (initPOSX - x * spacing, initPOSZ, initPOSY - y * spacing);
             _newObj = Instantiate(prefab, pos, Quaternion.identity);
             _newObj.name = "x" + x + "y" + y;
             //
             var tempName = _newObj.transform; //
             //Debug.Log(_newObj.name + " created at: Y " + _newObj.transform.position.y + " X " + _newObj.transform.position.x);
             // define _newObj as child of _parent
             _newObj.transform.parent = _parent.transform;
             //
             tempName = _parent.gameObject.transform.FindChild(tempName.name);
             
             // testing comunication with pathManager
             
             //var objName = _newObj.gameObject;
             
             Debug.Log("tempName is: " + tempName);
             pathmanager.AdGridBlock(tempName);
             
         }
     }
     Debug.Log("gridArray has: " + pathmanager.gridArray);
 }
 
 function Update () {
 
 }