Why does my Firewalld configuration on CentOS 7 fail to start and show iptables errors?

I'd like to:

1. Drop all incoming connections from the external Web except 80 and 443
2. Allow internal machines on 192.168.0.0/16 to connect to :9000 :8080

Here's what I did to setup my drop zone via firewall-cmd:

echo "net.ipv4.ip_forward=1" >> /etc/sysctl.conf
sysctl -p
systemctl start firewalld.service
systemctl enable firewalld
firewall-cmd --set-default-zone=drop
firewall-cmd --permanent --zone=drop --add-service=ssh
firewall-cmd --permanent --zone=drop --add-port=80/tcp
firewall-cmd --permanent --zone=drop --add-port=443/tcp
firewall-cmd --zone=drop --permanent --add-rich-rule='rule source address="192.168.0.0/16" port port="9000" protocol="tcp" accept'
firewall-cmd --zone=drop --permanent --add-rich-rule='rule source address="192.168.0.0/16" port port="8080" protocol="tcp" accept'
firewall-cmd --reload

Here's what the active drop zone looks like:

[root@machine ~]# firewall-cmd --zone=drop --list-all
drop (default, active)
  interfaces: eth0 vethadc7c41 vethaef84e2 vethd53fa38
  sources: 
  services: ssh
  ports: 443/tcp 80/tcp
  masquerade: no
  forward-ports: 
  icmp-blocks: 
  rich rules: 
  rule family="ipv4" source address="192.168.0.0/16" port port="9000" protocol="tcp" accept
  rule family="ipv4" source address="192.168.0.0/16" port port="8080" protocol="tcp" accept

This appears OK; however, I run into issues after reload:

[root@machine ~]# systemctl status firewalld -l
firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled)
   Active: active (running) since Sun 2014-12-21 19:48:53 UTC; 2s ago
 Main PID: 21689 (firewalld)
   CGroup: /system.slice/firewalld.service
           └─21689 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid

Dec 21 19:48:53 machine.hostname systemd[1]: Started firewalld - dynamic firewall daemon.
Dec 21 19:48:56 machine.hostname firewalld[21689]: 2014-12-21 19:48:56 ERROR: '/sbin/iptables -t filter -A DROP_allow -s 192.168.0.0/16 -m tcp -p tcp --dport 9000 -m conntrack --ctstate NEW -j ACCEPT' failed: iptables: No chain/target/match by that name.
Dec 21 19:48:56 machine.hostname firewalld[21689]: 2014-12-21 19:48:56 ERROR: '/sbin/iptables -t filter -A DROP_allow -s 192.168.0.0/16 -m tcp -p tcp --dport 9000 -m conntrack --ctstate NEW -j ACCEPT' failed: iptables: No chain/target/match by that name.
Dec 21 19:48:56 machine.hostname firewalld[21689]: 2014-12-21 19:48:56 ERROR: COMMAND_FAILED: '/sbin/iptables -t filter -A DROP_allow -s 192.168.0.0/16 -m tcp -p tcp --dport 9000 -m conntrack --ctstate NEW -j ACCEPT' failed: iptables: No chain/target/match by that name.
Dec 21 19:48:56 machine.hostname firewalld[21689]: 2014-12-21 19:48:56 ERROR: '/sbin/iptables -t filter -A DROP_allow -s 192.168.0.0/16 -m tcp -p tcp --dport 8080 -m conntrack --ctstate NEW -j ACCEPT' failed: iptables: No chain/target/match by that name.
Dec 21 19:48:56 machine.hostname firewalld[21689]: 2014-12-21 19:48:56 ERROR: '/sbin/iptables -t filter -A DROP_allow -s 192.168.0.0/16 -m tcp -p tcp --dport 8080 -m conntrack --ctstate NEW -j ACCEPT' failed: iptables: No chain/target/match by that name.
Dec 21 19:48:56 machine.hostname firewalld[21689]: 2014-12-21 19:48:56 ERROR: COMMAND_FAILED: '/sbin/iptables -t filter -A DROP_allow -s 192.168.0.0/16 -m tcp -p tcp --dport 8080 -m conntrack --ctstate NEW -j ACCEPT' failed: iptables: No chain/target/match by that name.

I'm a bit confused as I believed firewall-cmd to be an abstraction and sort of mutually exclusive with iptables, the latter being something I shouldn't mess with.

Here are my version vitals:

[machine@douglasii ~]# firewall-cmd -V
0.3.9
[machine@douglasii ~]# cat /proc/version
Linux version 3.16.7-x86_64-linode49 (maker@build) (gcc version 4.7.2 (Debian 4.7.2-5) ) #3 SMP Fri Nov 14 16:55:37 EST 2014
[machine@douglasii ~]# cat /etc/redhat-release
CentOS Linux release 7.0.1406 (Core) 
[machine@douglasii ~]# iptables -v
iptables v1.4.21: no command specified
Try `iptables -h' or 'iptables --help' for more information.