The registration opens everyday for about two hours at random, meaning there's no way to predict when it will open. You can read more about it here: Click Me! (http://www.feral-heart.com/index.php?option=com_jfusion&Itemid=2&jfile=index.php&topic=27243.0)
Make sure you have a free email when it opens!
It's usually closed to keep the server from lagging due to an excessive amount of players coming in at once.
I hope you catch it open sometime! I'm sure it'll come around. ;)