Custom installer woes (can't mount / RW)

Hi,
I'm trying to create a custom installer for FreeBSD to automatically setup our systems, however I am having a very odd problem.

The general idea is that I build a release, then create a chroot in which I install the slab of required ports for our system. I then tar that up and format a USB key (the same way it's done for a release) with the tar on it.

I then boot the USB key and go to the live FS and run my install script. It creates the file systems, unpacks the base distribution and my ports tar ball. Then I tweak various settings and reboot.

The problem I am having is that when I boot into the newly installed system I can't mount / RW, when I try it reports "Operation not permitted".

My script is at..
http://www.gsoft.com.au/~doconnor/install-os.sh

The odd thing (to me) is that I used the same gpart/newfs sequence when creating the USB stick and that can mount root RW just fine..

I tried booting verbose but there is no information forthcoming.

I am running SU+J however I tried disabling both on / and rebooting, but with no change.

The other partitions can be mounted RW just fine, and if I boot off other media I can mount what is / just fine as well.

If I install using bsdinstaller it works, so I have a work around, but I would like to use my custom script as it saves a lot of time and finger trouble.

Any help appreciated.

--
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
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