I've got a `plist` set to run at a set interval, and have put it in /Library/LaunchDaemons like so:

    /Library/LaunchDaemons $ ll macports_update_notifier.plist 
    lrwxr-xr-x  1 root  wheel    55B  5 Sep 13:47 macports_update_notifier.plist@ -> /Users/seron/bin/macports/macports_update_notifier.plist
The problem is that it doesn't seem to execute.
Here's the 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>EnvironmentVariables</key>
    	<dict>
    		<key>HOME</key>
    		<string>/Users/seron</string>
    	</dict>
    	<key>Label</key>
    	<string>macports_update_notifier</string>
    	<key>ProgramArguments</key>
    	<array>
    		<string>/Users/seron/bin/macports/macports_notificaton.sh</string>
    	</array>
    	<key>StartInterval</key>
    	<integer>300</integer>
    </dict>
    </plist>
I loaded it with `sudo launchctl load -w /Library/LaunchDaemons/macports_update_notifier.plist`.

Here's what `sudo launchctl list macports_update_notifier` produces:

    {
    	"Label" = "macports_update_notifier";
    	"LimitLoadToSessionType" = "System";
    	"OnDemand" = true;
    	"LastExitStatus" = 0;
    	"TimeOut" = 30;
    	"ProgramArguments" = (
    		"/Users/seron/bin/macports/macports_notificaton.sh";
    	);
    };

The script executes in about a second and works fine when run on its own. It needs to run as root.

I'm using OS X 10.8.1. What could be the problem?

**edit:**

My script runs [terminal-notifier](https://github.com/alloy/terminal-notifier) which is command line tool to display notifications in Mountain Lion and this is where the daemon bails.

    #!/bin/sh
    /opt/local/bin/terminal-notifier -message 'output' -group 'debug'

I found that the daemon runs fine if it's not loaded with `sudo`. One difference is that `launchctl load test.plist` reports `"LimitLoadToSessionType" = "Aqua"` instead of `"System"`. However if I set `LimitLoadToSessionType` to `Aqua` in the plist and load with `sudo` `launchctl` refuses to load it displaying `nothing found to load`. It needs to run as root however because it updates the macports database.