Paypal link only shows up as %PayPalLink%

Paypal link only shows up as %PayPalLink%

I have done a mock invoice and sent it to one of my email addresses just to beta test the invoice function of my business. 
In the email I received, all I can see is the same typed characters -- " % PayPal % " but includes no actual PayPal link that can be clicked and - you know - linked to a PayPal destination where customers will ultimately pay me.....so what do you think I need to correct in order to fix this and collect the money I am owed?