Quantity not allowed for this item

Been using the User Event Script that adds line(s) to a Sales Order AfterSubmit Call.

All I do is:
soRecord.insertLineItem('item',i);
            soRecord.setLineItemValue('item', 'item', i, itemID);//Sub-Total Item
            soRecord.setLineItemValue('item', 'description', i, itemDesc);
            soRecord.setLineItemValue('item', 'amount', i, '0');


I was not setting the Quantity Previously and this was working. NetSuite defaulted this to ‘1’ for all items except Sub-total Items which should not have a quantity. But now Sub-total items quantity is getting set to 1, and I am getting this error:

Title USER_ERROR 
Type System  
Details Quantity not allowed for this item. 

Madhuri