Instantiate a Class picked from a Class Array

[5TonsOfFlax]

Are you sure that the objects in your class array are Classes? Does range return a single random integer in the specified range?

If both of those are true, it should work.

I suspect you have something other than classes in your array (such as String), causing objClass to be null.

[cancerinform]

This example will give you the error you got, because Green is a string:

var myArray:Array = new Array("Green");
var objClass:Class = myArray[0] as Class;
var objisplayObjectContainer = new objClass() as DisplayObjectContainer;
addChild(obj);

Changing the first line will correct the mistake:
var myArray:Array = new Array(Green);

Probably the array members are all strings.