blank side OOP

PHP kode 

 <?php
 require 'include/connect.php';
 class UserLogin {
     function godkendt($username, $password) {
 
         $mysql = connect();
         $stmt = $mysql->prepare("SELECT username, password WHERE username = '$username' AND password = '$password'") or die(mysql_error());
         $stmt->execute();
         $stmt->bind_result($username,$password);
         $stmt->fetch();
 
         if($stmt == 1){
             $reponse = "Du er logget ind";
         } else {
             $response = "Der var fejl i dit brugernavn eller password";
         }//Lukker else
     }// Lukker godkendt
 }//Lukker UserLogin
 ?>

PHP kode 

 <?php
 
 if(isset($_POST['login'])) {
     require 'classes/UserLogin.php';
 
    $username = $_POST['username'];
    $password = $_POST['password'];
    
    $ul = new UserLogin();
    $ul->godkendt($username, $password);
 
    echo $respons;
     
 }
 
 ?>

PHP kode 

 <?php
 function connect() {
     $mysql = new mysqli('localhost', 'root', '', 'rapcom2') or die('Der var et problem med at connecte til databasen');
     return $mysql;
 }
 ?>