install.cfg disklabel failure when PXE booting

[Don]

I am attempting to set up network installs of FreeBSD 5.2.1 for a project
I am working on.

I can boot kern.flp and mfsroot.flp over the network with no problems and
do a manual install.

I can configure install.cfg to automatically set the distribution, network
card, install method and so on.

What I can not get working right is automatic disk partitioning.

No matter what I have set up, the installer just will not set up
partitions for me.

install.cfg looks like:
# Now set the parameters for the partition editor on ad0
disk=ad0
partition=all
bootManager=standard
diskPartitionEditor
#diskPartitionWrite

# All sizes are expressed in 512 byte blocks!
ad0s1-1=ufs 1999999 /
ad0s1-2=swap 6485760 none
ad0s1-3=ufs 2097152 /var
ad0s1-4=ufs 0 /usr
# Let's do it!
diskLabelEditor
#diskLabelCommit

Can anyone tell me where I am screwing up? I have tried several variations
on the above config file all without success. There is also the somewhat
related problem of sysinstall refusing to accept the BIOS definition of
the drive geometry but I believe I was able to get beyond that problem.

Thanks in advance,
-Don