Help with fwmark and shorewall

I'm using shorewall, 2 ISP connections, and I want to force udp 500 traffic out one particular interface

here's what I have so far /etc/shorewall/tcrules:

4       0.0.0.0/0       202.37.230.93   udp     500
4       202.37.230.93   0.0.0.0/0       udp     500

shorewall show mangle | grep MARK
14 4203 MARK udp -- * * 0.0.0.0/0
202.37.230.93 udp dpt:500 MARK set 0x4

    0     0 MARK       udp  --  *      *       202.37.230.93 

0.0.0.0/0 udp dpt:500 MARK set 0x4

routing:
/sbin/ip rule add prio 223 fwmark 4 table 223

/sbin/ip route add default via 202.37.230.65 dev eth2 \
         src 202.37.230.93 proto static table 223

routing rules:
ip rule show

0:      from all lookup local
50:     from all lookup main
201:    from 202.37.230.64/26 lookup 201
202:    from 203.96.212.0/23 lookup 202
222:    from all lookup 222
223:    from all fwmark 0x4 lookup 223
32766:  from all lookup main
32767:  from all lookup default

ip route show table 223
default via 202.37.230.65 dev eth2 proto static src 202.37.230.93

the load balancing work flawlessly :)
however I have racoon (kernel 2.6.8.1) on the firewall, and only sometimes it responds using 202.37.230.93 .. sometimes it uses my other ISP connection .. which is no good :(

I've got to the point where I guess I need to use fwmark before routing, but it doesn't seem to work :(

Any help

Thanks
Paul.