ipnat failed at NetBSD-current (2.0B 04/02)

# cat /etc/ipnat.conf
map wm0 192.168.*.*/24 -> 0/32 proxy port ftp ftp/tcp
map wm0 192.168.*.*/24 -> 0/32 portmap tcp/udp auto
map wm0 192.168.*.*/24 -> 0/32
#
# ipnat -l
List of active MAP/Redirect filters:

List of active sessions:
#
# ipnat -f /etc/ipnat.conf
2:ioctl(add/insert nat rule): Invalid argument
3:ioctl(add/insert nat rule): Invalid argument
2:ioctl(add/insert nat rule): Invalid argument
#
# ipf -V
ipf: IP Filter: v4.1.1 (480)
Kernel: IP Filter: v4.1.1
Running: yes
Log Flags: 0 = none set
Default: pass all, Logging: available
Active list: 0
Feature mask: 0x10a
#