Custom Quote Field not showing correctly when Print Quote For Customer is Executed

Hello Community,

I have a custom field for Quote that I set with a javaScript - https://community.dynamics.com/crm/f/117/t/111553.aspx#.Uh-Oo9K1FCY .  This field is read-only and not visible on the form.  This field is empty by default.  When I Print Quote For Customer, on the mail merge document, this field is always showing empty.  I can get it to not show empty, if I make the field visible and editable on the form.  I'm not sure why this is occuring, and your help would be appreciated.