8.45.1 on mac - Plist problems

Hi all,
Using a MacBook Pro. Snow Leopard installed along with XCode

I have 8.4.1 compiled from tar.gz. It lives in
/usr/local/postgresql-8.4.1 which is owned by root. the data
subdirectory is owned by postgres. A link exists from
/usr/local/postgres to postgresql-8.4.1.

PGDATA is /usr/local/postgres/data

I can run okay with /usr/local/postgres/bin/postmaster -D ${PGDATA}

I have tried to copy/build/modify a plist to start up automatically.
The file below is named org.postgres.launchd.plist and it is in
/Library/LaunchDaemons. I have fashioned it after dBEnterprises'.

file:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN"
"http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Disabled</key>
<false/>
<key>Label</key>
<string>org.postgres.launchd</string>
<key>ProgramArguments</key>
<array>
<string>/usr/local/postgres-8.4.1/bin/postmaster</string>
<string>-D</string>
<string>/usr/local/postgresql-8.4.1/bin</string>
</array>
<key>RunAtLoad</key>
<true/>
<key>UserName</key>
<string>postgres</string>
</dict>
</plist>

after saving, I
launchctl load /Library/LaunchDarmons/org.postgres.launchd.plist
then
launchctl list | grep postgres returns
2 org.postgres.launchd

but when I
launchctl start org.postgres.launchd
Nothing happens. ps ax |grep postmaster does not show
postmaster running.

Any ideas or assistance is greatfully appreciated.

Bob