Internet <-> Router with netfilter configure <-> LAN(192.9.201.0/24)

lets supopose eth0 is LAN side Interface and
eth1 is WAN side interface.

what I want to do is "Mark all h323 packets with some tos value".
for which my iptables  command seems to be like this-
     iptables -t mangle -A FORWARD -o eth0 -d 192.9.201.0/24 -p tcp -m rtp -j FTOS --set-ftos 0xb8.

but it's giving an error message -
iptable: No chain/target/match by tha rule.

Can anybody help me out.

Thanks & Regards
Upma