error with buildkernel

Hi,

I don't know why I got this error.
It said
/usr/src/sys/netinet/ip_divert.c:40:2: #error "IPDIVERT requires IPFIREWALL"

but my kernel configuration has the following options defined:

options IPFIREWALL #firewall
#options IPFIREWALL_VERBOSE #print information about
options IPFIREWALL_DEFAULT_TO_ACCEPT #allow everything by default
#options IPSTEALTH
options IPDIVERT
options TCP_DROP_SYNFIN

Can anyone tell me what's wrong?
I have clean up all object files from the /usr/obj directory before start building the kernel.

Thanks
Sam
.