iptables v1.3.4: STRING match: You must specify `--algo'

[Jasbir Khehra]

Hi,
   while  running this command
# iptables -t nat -I PREROUTING -p tcp -s 192.168.2.20 -m string
--hex-string '0d0a0d0a594d5347' -j REJECT

Not able to get the different options for '--algo' parameter . 
Kernel 2.6.14 iptables v1.3.4  thanks - Jasbir