[CentOS] Iptables port forwarding help

Hello,

I have a webcam that I wish to view from the internet.  It is a wireless
linksys model with an ip address of 192.168.1.15.  I have it set on port
8081, 192.168.1.15:8081.

I am using the IP Masquerade HowTo script.  Here's the rule I added to my
firewall script:

EXTIF="ppp0"
INTIF="eth1"
EXTIP="`$IFCONFIG $EXTIF | grep inet | cut -d : -f 2 | cut -d \  -f 1`"


$IPTABLES -A FORWARD -i $EXTIF -o $INTIF -p tcp --dport 8081 -m state \
 --state NEW,ESTABLISHED,RELATED -j ACCEPT

$IPTABLES -A PREROUTING -t nat -p tcp -d $EXTIP --dport 8081 \
 -j DNAT --to 192.168.1.15:8081

Its not working.  Can anyone offer a suggestion?

TIA