Transaction Item Count Script

Hello,
I have an existing script that works to give me the total quantity of inventory units on an order and the total quantity of inventory units which have been billed. Now, I want to add a new field which shows the Total Units Committed on the order. I'm having trouble adding this logic to the existing script. Can anyone see what might be wrong?

function calculatePOqty(type, name){
var c = nlapiGetLineItemCount('item');
var itemCount = 0;
var itemBill = 0;
var itemCommitt = 0;
var result;

for (var i = 1; i <= c; i++) {
var item_type = nlapiGetLineItemValue('item', 'itemtype', i);
if (item_type == 'InvtPart') {
itemCount += parseInt(nlapiGetLineItemValue('item', 'quantity', i), 10);