iptables assistance

I have a CentOS 5.2 (10.20.21.73) machine that I need help with configuring iptables. According to documentation I believe this line should allow all communication between my machine and another machine (other machine has no firewall)

-A RH-Firewall-1-INPUT -s 10.20.21.12 -j ACCEPT

# /etc/sysconfig/iptables
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A FORWARD -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INPUT -s 10.20.21.12 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited
COMMIT

Ahh, after much fiddling around with different configurations, I found the answer.

Needed my subnet on the source, 10.x.x.x/255.255.255.0 solved the problem.