Gravity Forms hook to stop a form from loading

gravity_forms_example_1.php

add_filter('gform_pre_render', 'swp_populate_attendee_list');
function swp_populate_attendee_list($form){

	$num = swp_get_the_amount();

	if ( count( $num ) < 1 ) {
		add_filter('gform_get_form_filter', create_function('', "return 'You have not met the condition! Please go to <a href=\"/?page_id=1\">this form.</a>';") );
	}

	return $form;
}