You have also to uncomment auto.hotplpug or use auto.network from file /etc/auto.master like below..
K.
auto.master
#
# $Id: auto.master,v 1.4 2005/01/04 14:36:54 raven Exp $
#
# Sample auto.master file
# This is an automounter map and it has the following format
# key [ -mount-options-separated-by-comma ] location
# For details of the format look at autofs(5).
#/smb /etc/auto.smb
#/net /etc/auto.net
#/autofs /etc/auto.hotplug
/media/net /etc/auto.network