Help a beginner with a small doubt ?

I just started learning unity and now I just started learning UnityScript API's. In this below script I am able to do everything I am doing for the object and its working properly but in below the code I am trying to access function from another script and it shows me an error message.

"NullReferenceException: Object reference not set to an instance of an object CubeBehaviour_01.Update () (at Assets/Scripts/CubeBehaviour_01.js:22)"

Here is the code

 CubeBehavious.JS
 
 var CubeSpeed = 1;
 
 var accessVariable : GameObject;
 
 function Update () {
     
     this.transform.Translate(0,0,Time.deltaTime*CubeSpeed,Space.Self);
     
     //Rotate the Object -> Cube.
     this.transform.Rotate(0,0,1);
     
     accessVariable.transform.Translate(0,0,Time.deltaTime*CubeSpeed,Space.Self);
     
     var accessScript = GetComponent(SecondScript);
     accessScript.newFunction("Hello");
 
     }
   
 SecondScript.js
     
 function Update () {
     
 }

 function newFunction (s : String)
 
 {
     var newSpeed = 10;
     print("Hello World " + newSpeed);
 }

this newFunction is the function I am accessing.

Sorry if this is a very basic question. I am just a beginner . Thank you for your time.