How do I change kern.ipc.shmmax in FreeBSD 5.x automatically after reboot?

[Kipp Holger]

Hello,

I have the following entries in /boot/loader.conf:

  kern.ipc.shm_use_phys="1"
  kern.ipc.semmns="500"
  kern.ipc.semmni="40"
  kern.ipc.semmap="500"

which are set correctly. Unfortunately, the following
two entries

  kern.ipc.shmmax="512000000"
  kern.ipc.shmall="65526"

do not change the corresponding values according
to sysctl, no matter whether I put them in 
/boot/loader.conf or /etc/sysctl.conf.

Changing them by hand (as root with 'sysctl') afterwards
however _does_ work, so I have (for now) put
those two settings in a little script
(/usr/local/etc/rc.d/000_sysctl.sh)

Has this behaviour changed for 6.x?
Anyone who could explain this behaviour?

Regards,
Holger