Include invoice number on PDF?

How do I include the invoice number on the PDF receipt?  The config page makes it sound like it will be included automatically but it is not appearing on my PDF receipts. 
 

Hi Chad,
You can use tag [INVOICE_NUMBER] in the invoice template, it will be replaced by invoice number
Thanks
Dam

Thank you. That seems to work fine for the PDF and I see an invoice number in the final PDF attachment but when I put the same thing in the User email body field the email is delivered with only a zero for the invoice number. See the video below to see what I mean.

screenrec.com/share/rAKpnzfSaM

Hi Chad,
Maybe the invoice number hasn't generated, and that's the reason it shows 0 in the email content. I think you had better to use the Invoice number in PDF layout only.
Thanks
Dam