Error: Null Reference Exception

I have an error in my Array, but i couldnt figure out why it was null. What am I doing wrong?

Error NullReferenceException: Object reference not set to an instance of an object

The object that i have placed in Scroller, has 4 child game objects (planes) under it. The error states that its a problem with where I am setting the values of the levels array;

please help!

 using System;
 
 
 [Serializable]
 public class Levels 
 {
     public GameObject levelImage;
     public GameObject locked;
     public bool isLocked;
 }
 
 public class LevelSelectMenu : MonoBehaviour {
 
 public GameObject scroller;
     public Levels[] levels;
 
 void Awake ()
 {
 if (scroller && levels.Length == 0)
         {
             
             int children = scroller.transform.childCount;
             print (children);
             levels = new Levels[children];
             for (int i = 0; i < children; i++ )
             {
                 levels[i].levelImage = scroller.transform.GetChild(i).gameObject;
                 levels[i].locked = levels[i].levelImage.transform.GetChild(i).gameObject;
                 levels[i].isLocked = GlobalState.levelStats[i].locked;
             }
         }
 }
 }