Sistema de Login

Olá a todos!

Quando eu tento fazer o login me mostra esse erro "Could not log you in."; Alguém sabe me ajudar a resolver esse problema no meu código?

<?php
require_once("core/init.php");

if (Input::exists()) {
if (Token::check(Input::get("token"))) {

 $validate = new Validate();
 $validation = $validate->check($_POST, array(
 "username" => array("required" => true),
 "password" => array("required" => true)
 ));

 if ($validation->passed()) {
 $user = new User();

 $remember = (Input::get("remember")) === "on" ? true : false;
 $login = $user->login(Input::get("username"), Input::get("password"), $remember);

 if ($login) {
 Session::flash("home", "Welcome back!");
 Redirect::to("index.php");
 } else {
 echo "Could not log you in.";
 }
 } else {
 foreach ($validation->errors() as $error) {
 echo $error."<BR>";
 }
 }
 }
}

?>

<form action="" method="POST">
 <div class="field">
 <label for="username">Username</label>
 <input type="text" name="username" id="username">
 </div>
 <div class="field">
 <label for="password">Password</label>
 <input type="password" name="password" id="password">
 </div>
 <div class="field">
 <label for="remember">
 <input type="checkbox" name="remember" id="remember"> Remember me
 </label>
 </div>
 <input type="hidden" name="token" value="<?php echo Token::generate(); ?>">
 <input type="submit" value="Log in">
</form>

	 

	 

	Desde já obrigado.