Why will iptables not start?

Issue

• The iptables service will not start, even though it is configured to start at boot and none of the kernel modules are blacklisted
• There is no error seen, simply Firewall is stopped:

    [root@rhel5u11 ~]# service iptables start
    [root@rhel5u11 ~]# service iptables status
    Firewall is stopped.