hitTest Multiple targets

Greetings All,
I have a question about hitTest, and I was wondering if anyone can help me. I have an object in the display set called redBall. Each frame, I want test to see if the ball is touching any of the other objects on the stage, with instance names: platForm1, platForm2, or platForm3.

My idea was to create an array that contains the name of each of the “platForm” object. Each frame, I loop through the array to see if the ball is touching any of the objects named in the array. Here is the basic code, I’ve stripped out includes, any any other extraneous code:

var hitObject:Array = new Array(); //This array will hold the name of each platform
hitObject.push(platForm1); //Push each platform object into the array
trace(hitObject.length); //Traces "3", good!
trace(typeof hitObject[0]); //Traces "object", good!
function onNewFrame(e:Event):void{
 for(var i:Number = hitObject.length; i>0; i--){
   trace("nope, not touching this object");

The problem is that I’m getting a 2007 error:

TypeError: Error #2007: Parameter hitTestObject must be non-null.
at flash.display:DisplayObject/_hitTest()
at flash.display:DisplayObject/hitTestObject()
at array_fla::MainTimeline/onNewFrame()

…Can anyone help me figure out what’s going on here? I think either I am placing the wrong type of object into the array, or I am using the wrong property to test my hit.