Customer List ordering by last name?

[csparks903]

I have tried multiple ways to order my customer list by last name. If I put lastname,firstname it prints on the envelope that way. I have tried contact name, first name, customer name in various ways with just last name for customer name and first name in first name field. This may just be the way it is written or am I over looking something. Maybe a "trick" to get it to work.