getFieldValue('createdfrom') is null

I've spent the weekend fighting this.

I have the following code for when we "Receive" items from Purchase Orders:

What I need is to get the internalid of the Purchase Order that the receipt was created from but it is always blank.

Doesn't matter if I do before_submit or after_submit, it is always null:)

Can anybody see what I am doing wrong?

Thanks, Shanon

  currentRecord = nlapiGetNewRecord();    po_id = currentRecord.getFieldValue('createdfrom');    debug_output('Audit', "PO", po_id);  //  po_id = "110168";    //Load the PO so that we can get data from it    var orig_po_record = nlapiLoadRecord('purchaseorder', po_id);