Zero Discount Value On Sales Order Invoices

SUGGESTED

Is there a way/formulae I can use to include the value zero (0), on Invoice documents for invoice lines that do have zero discounts (Instead of a blank space appearing on the invoice layout)?

The current setup is that, when an invoice line has a zero discount, the discount column space under the invoice layout appears as blank (As Per Screenshot 1).

Changing the layout field to read Blank when Zero, does not result to any changes. 

How can we make the discount field on the layout to show the figure zero (0), when printing ?