SIngleton Array problem (Array Index out of Range, but index = 0)

So my problem is within my referenceManager that handles common GameObject references. These are all singletons. my singleton stuff is done with this:

    private static referenceManager m_Instance = null;
    public static referenceManager Get()
        if (m_Instance == null)
            m_Instance = (referenceManager)FindObjectOfType(typeof(referenceManager));
        return m_Instance;

the length of my array is set in editor, i fill it with the following code in void Awake:

        for (int c = 0; c < Collectibles.Length; c++)
 = GameObject.Find("Collectible" + (c+1));
This all seems to work, because in editor it is all filled in.
When i now try to reference the array in different scripts with smth like this...:

...i get the followeing error message:

> IndexOutOfRangeException: Array index is out of range.
> collectibleManager.Start () (at Assets/scripts/paths/collectibleManager.cs:32)
Since i also had some other issues with the array i think i do smth wrong, but i dont know what. Ive searched all over google for explanantion, but couldnt find someone with my exact problem. Any help is very appreciated.

I tried out gameObjects Lists instead and now it works perfect.