Specifying Driver

I am trying to specify the driver for the HP Laserjet M606 printer, and the driver is listed in lpinfo -m as lsb/usr/HP/hp-laserjet_m604_m605_m606-ps.ppd.gz HP Laserjet M604 M605 M606 Postscript
writing Driver=HP Laserjet M604 M605 M606 Postscript
in my printers.conf does not work.  when trying to install it, it gives me an error that no printer drivers were found.  What am I doing wrong?