Trouble with comboBox addItem

1

I have a comboBox that I want to populate with data from an XML file. It won’t cooperate.
this works:

sFoC.shippingMethod_cb.addItem("hello");

but this doesn’t:

populatePulldown = function (elements) {
     trace(elements[0].attributes.label);//returns "Fast"
     trace(elements[0].attributes.cost);//returns "15.00"
     for (i=0; i<elements.length; i++) {
         sFoC.shippingMethod_cb.addItem(elements*.attributes.label, elements*.attributes.cost);
     }
 }

It won’t add anything to the cb. I don’t understand why. Both these code snippets were in the same place.
Any ideas??
-Joshua