redirect doesn’t work with crypt function

when i crypt password before login, redirect function doesn’t work
but when i doesn’t use crypt function login works and redirect to new page

this code doesn’t work

$password = crypt($password, $salt);

if ($username == $db_username && $password == $db_user_password) {
    $_SESSION['username'] = $db_username;
    $_SESSION['firstname'] = $db_user_firstname;
    $_SESSION['lastname'] = $db_user_lastname;
    $_SESSION['user_role'] = $db_user_role;
    header("Location: ../admin/index.php");   
}

but this code work

if ($username == $db_username && $password == $db_user_password) {
    $_SESSION['username'] = $db_username;
    $_SESSION['firstname'] = $db_user_firstname;
    $_SESSION['lastname'] = $db_user_lastname;
    $_SESSION['user_role'] = $db_user_role;
    header("Location: ../admin/index.php");   
}

i remove crypt and problem solved