Missing Method in EnquiriesController

Error: The action captcha_image is not defined in controller EnquiriesController

Error: Create EnquiriesController::captcha_image() in file: app/controllers/enquiries_controller.php.

<?php
class EnquiriesController extends AppController {

	var $name = 'Enquiries';


	function captcha_image() {

	}

}
?>

Notice: If you want to customize this error message, create app/views/errors/missing_action.ctp