.plist not keeping process alive

Question

I am trying to setup FreeRADIUS on a Mac Server. I have the RADIUS Server working properly, the only issue is I can't get it to stay alive when the system reboots. The following is a plist I have in /Library/LaunchDaemons/org.freeradius.radiusd.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
  "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>KeepAlive</key>
    <true/>

    <key>RunAtLoad</key>
    <true/>

    <key>EnableTransactions</key>
    <true/>

    <key>Label</key>
    <string>org.freeradius.radiusd</string>

    <key>StandardErrorPath</key>
    <string>/tmp/mycommand.err</string>

    <key>StandardOutPath</key>
    <string>/tmp/mycommand.out</string>

    <key>ProgramArguments</key>
    <array>
      <string>/usr/local/bin/radiusd</string>
      <string>-X</string>
      <string>-d</string>
      <string>/usr/local/etc/raddb</string>
    </array>
  </dict>
</plist>

After I restart and then use the following command

sudo launchctl load -w /Library/LaunchDaemons/org.freeradius.radiusd.plist

the server launches fine without any issues and it stays alive.

I've had a look at output in /tmp/mycommand.out (.err is empty) and the last couple of lines are:

Listening on auth address * port 1812 bound to server default
Listening on acct address * port 1813 bound to server default
Listening on auth address :: port 1812 bound to server default
Listening on acct address :: port 1813 bound to server default
Listening on auth address 127.0.0.1 port 18120 bound to server inner-tunnel
Listening on proxy address * port 53565
Listening on proxy address :: port 53566
Ready to process requests

so it seems to be launching okay.

I have also checked the permissions on the plist and they are the following

-rw-r--r--   1 root  wheel   738 27 Jun 11:41 org.freeradius.radiusd.plist

Any ideas?