CODEIGNITER ROOKIE

[eluser]Cro_Crx[/eluser]
Before you create a checker in AJAX, it's probably best to try one in just plain PHP and then once you get that concept then create an AJAX one.

You'll need to create a callback function for your form validation class. Here's the link http://ellislab.com/codeigniter/user-gui...#callbacks

Let me know if your still stuck, I can post some code snippets if you'd like.