Building an array of movie clips

Question

Hi
I have a main document class and an array class (amongst others).
I am not sure how to build the array though. Below is my attempt up to now. But I get the following error code.
TypeError: Error #1009: Cannot access a property or method of a null object reference.
    at LetterArray/initLetters()
    at LetterArray()
    at BugGoopFSGame() //This is my main document class.
What am I doing wrong?
Thanks
Charine
//in main document class
public var letterArray:LetterArray = new LetterArray(stage);
//in array class
package
    import flash.display.MovieClip;
    import flash.events.Event;
    import flash.events.MouseEvent;
    import flash.display.Stage;
    public class LetterArray extends MovieClip
        private var _stage:Stage;
        /*The following are movie clips that need to go into an array so that they can be manipulated togehter.
        Their classes A, F, G, H, I, N, O, S  and T were all dynamically created by flash.*/
//Do I even need these here?
        public var a:A;
        public var f:F;
        public var g:G;
        public var h:H;
        public var i:I;
        public var n:N;
        public var o:O;
        public var s:S;
        public var t:T;
         public function LetterArray(s:Stage)
            _stage = stage;
            initLetters();
        private function initLetters():void
            var LetterArray:Array = new Array[a,f,g,h,i,n,o,s,t];
//rest not relevant

Answer 1

You declare a bunch of objects but you do not instaintiate them.
public var a:A;  // declare but does not yet exist
public var a:A = new A();   // declared and exists