mysqli class error

<?php
include('includes/mysqli.inc.php');

class Edit {
	
	public $connection;
	
	function __construct(){
		$this->connection = new mysqli(DB_HOST, DB_USER, DB_PASSWORD, DB_DATABASE);
	}
	
	function __destruct(){
		$this->connection->close();
	}
	
	public function display($klant) {
		// maak query
		$result = $this->connection->query("SELECT * FROM `klanten_contact_gegevens` WHERE `klantnr`='$klant'");
		// sla alles op in een array
		$array = $result->fetch_array();
		// geef alles terug
		return $array;
	}
}
?>

<?php
include('includes/mysqli.inc.php');
 
class Edit {
 
	public $connection;
 
	function __construct(){
		$this->connection = new mysqli(DB_HOST, DB_USER, DB_PASSWORD, DB_DATABASE);
	}
 
	function __destruct(){
		$this->connection->close();
	}
 
	public function display($klant) {
		// maak query
		$result = $this->connection->query("SELECT * FROM `klanten_contact_gegevens` WHERE `klantnr`='$klant'");
		// sla alles op in een array
		$array = $result->fetch_array();
		// geef alles terug
		return $array;
	}
}
?>