The circuit goes from the +5v of the regulator, thru the LED, thru the resistor to Port 4. So this means you must set port4 LOW in order to turn on the LED. This has been a confusion to a lot of people. Can't say why Admin did it this way to start with other than: since ports seem to default to being LOW then the LED will turn on by default - so by default it is a Power On/Off inidicator. A common issue that people have is that they wire the LED the wrong way around - now you know why.