@mattdahse I think there is something wrong with this line: // created the Inventory Detail Sub-record for the Lot Numbered Item. var subRecord = fulfillment.getCurrentSublistSubrecord({ sublistId: 'item', fieldId: 'inventorydetail' }); // Create a new line in the sub-record. subRecord.selectNewLine({ sublistId: 'inventoryassignment' }); The way I understand it, the code is getting the subrecord of the current line but no line is selected before that code