If an imported order comes in with an item that has a stock ID of 0, this means that the item is not linked to a stock code and a stock code must be created before you are able to progress this order.
To do so, highlight the product line and then select 'Make Product'.
If an error message is returned when trying to make the product, this is usually due to the stock code already existing on the system. To check this, go to stock - products and search for the code that you are trying to create, if this product is returned in the results you will need to discontinue this code and re-create the item from the imported order.
If the item does not show, change the status in the drop down to 'Discontinued' and search again. You will then need to add the pre-fix DIS to this stock code.