How can I sort an array with objects in?

I want to sort an array that contains object references.
I want to sort on one of the values held by the objects.

I have the following sample code, say:

   ActionScript:abc = new Array();
   abc[0] = new Object();
   abc[0].anotherObj = new Object();
   abc[0].anotherObj.myNumber = 21;
   abc[1] = new Object();
   abc[1].anotherObj = new Object();
   abc[1].anotherObj.myNumber = 11;
   abc[2] = new Object();
   abc[2].anotherObj = new Object();
   abc[2].anotherObj.myNumber = 2;
   abc[3] = new Object();
   abc[3].anotherObj = new Object();
   abc[3].anotherObj.myNumber = 3;
   abc.sortOn("anotherObj.myNumber", Array.NUMERIC);

In the above code… I want to sort on anotherObj.myNumber.
The above doesn’t work.
I wasn’t sure what I should put for anotherObj.myNumber??

Any help would be appreciated.