FC6 Automount Problem

I just upgraded one of our machines from FC5 to FC6. After the process, the automount failed during startup. This is the message from the log.

master_read_master: can't read master map auto.master

This is strange, because there is an auto.master file in the /etc directory. I then modified the /etc/sysconfig/autofs and uncommented DEFAULT_MASTER_MAP_NAME and set it to /etc/auto.master . The setting is now like the following.

DEFAULT_MASTER_MAP_NAME="/etc/auto.master"

After the modification, I restarted autofs and it started to work again.