Mac – LaunchDaemon not recognised

I've installed CouchDB via MacPorts. Now I want to start it when my Mac boots, so I executed the instructions given in the install process:

sudo launchctl load -w /Library/LaunchDaemons/org.apache.couchdb.plist

However this doesn't seem to work. I've looked inside the LaunchDaemons directory, and the plist file is there (as a symlink):

lrwxr-xr-x  1 root  wheel   57 18 aug 10:11 org.apache.couchdb.plist -> /opt/local/Library/LaunchDaemons/org.apache.couchdb.plist

The contents of the actual plist file seem ok (however I have no real knowledge of how it should look):

<plist version="1.0">
  <dict>
    <key>Label</key>
    <string>org.apache.couchdb</string>
    <key>EnvironmentVariables</key>
    <dict>
      <key>HOME</key>
      <string>~</string>


    </dict>
    <key>ProgramArguments</key>
    <array>
      <string>/opt/local/bin/couchdb</string>
    </array>
    <key>UserName</key>
    <string>couchdb</string>
    <key>StandardOutPath</key>
    <string>/dev/null</string>
    <key>StandardErrorPath</key>
    <string>/dev/null</string>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
    <true/>
  </dict>
</plist>

When I execute /opt/local/bin/couchdb manually, the process is created, so no problems there. It just seems the launch daemon skips this command.

Any thoughts on how to fix this?