[K12OSN] iptables and prerouting for squid

[KJ]

Hello all,
I FINALLY have squid/squidguard working.  If I enter 127.0.0.1 port 3128 
as my proxy, everything works fine.  The issue that I am having (the 
last before deployment, I think) is that I can't get iptables to route 
all traffic to port 3128.
When I reinstalled K12 LTSP I made sure to initiate a firewall.  Now I 
have entries in iptables for the RH-Firewall chain.  When I enter:

iptables - t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT 
--to-port 3128

nothing happens.  I've tried flushing and re-entering the above 
statement, still nothing.

Any help would be greatly appreciated.
Thanks!
KJ