KeyboardEvent.KEY_DOWN. Some keys work, others dont

I want to run a function when the enter key is pressed.
I believe the following code is correct:


stage.addEventListener(KeyboardEvent.KEY_DOWN, selectDetect);

public function selectDetect(event:KeyboardEvent):void 
	{
		if (event.keyCode == Keyboard.ENTER) 
                {
                 ..........
                 .....
                 ..
                }

	 }

However, nothing happens! If I change the code to Keyboard.SPACE it runs when the space bar is pressed. It seems strange to me. Any one else come across this?