ipdivert rule will not load

[freebsd at stateautomation.com (freebsd_(_at_)_stateautomation_(_dot_)_com)]

ipfw will not accept a DIVERT rule. e.g the rule I am trying to add is.. 
ipfw add 3000 divert 8668 ip from any to any via sis0 
The response I get is... ipfw: getsockopt(IP_FW_ADD): Invalid argument 
I have built a custom kernel with the following optional lines 
options IPFIREWALL 
options IPFIREWALL_VERBOSE 
options IPFIREWALL_VERBOSE_LIMIT 
options IPDIVERT 
Does anyone know why the system will not accept the divert rule?  Thankyou.

J.S.