Printers.conf restart

I have made some additions to printers.conf to allow/deny users access to a printer. I there something I have to restart in order to get my changes recognised. I ask this because i have specified certain users cant use a printer. So I tested what I had done and It appeared not to work. Does anyone know what Im doing wrong? Cheers -- Andrew Nix St Pauls Catholic High School Firbank Road Newall Green Wythenshawe Manchester M23 2YS tel: 0161 4375841 ext 168 fax: 0161 4982030