I made a webapplication with login. Based on the role it should go to a indexpage in a different folder depending on the role the user has. On my local machine (with the use of MAMP Pro) it works perfectly, but when i copy the whole folder to my hosting (with the right connection to the database in my hosting) it will show that a user is logged on, but doesn't redirect to the folders. the Header comes within the Session_start() storage.
<?php
define("TITLE1", "Inlog"); 
session_start();
include('includes/header.php'); 
if( isset( $_POST['login'] ) ) {
    $formUser = validateFormData( $_POST['username'] );
    $formPass = validateFormData( $_POST['password'] );
    $query = "SELECT * FROM `werknemers` WHERE `username`='$formUser'";
    $result = mysqli_query( $link, $query );
    if( mysqli_num_rows($result) > 0 ) {
        while( $row = mysqli_fetch_assoc($result) ) {
            $id = $row['werknemerid'];
            $user       = $row['username'];
            $email      = $row['email'];
            $hashedPass = $row['password'];
            $role = $row['role'];
        }
        if( password_verify( $formPass, $hashedPass ) ) {
            session_start();
            $_SESSION['loggedInUser'] = $user;
            $_SESSION['loggedInEmail'] = $email;
            $_SESSION['loggedInRole'] = $role; 
            $_SESSION['loggedInID'] = $id;
            if($role == 'planner'){
                header('location: planner/indexplanner.php');
                exit();
            }  else if($role == 'werknemer'){
                header('location:werknemer/indexwn.php');
                exit();
            }
        } else {
            $loginError = "<div class='alert alert-danger'>Wrong username / password combination. Try again.</div>";
        }
    } else {
        $loginError = "<div class='alert alert-danger'>No such user in database. Please try again. <a class='close' data-dismiss='alert'>×</a></div>";
    }
    mysqli_close($link);
}
?>
<div class="container">
    <div class="row">
        <div class="col-md-2"></div>
        <div class="col-md-8">
            <h1>Login</h1>
            <p>Use this form to log in to your account</p>
            <?php echo $loginError; ?>
            <form class="form-inline" action="<?php echo htmlspecialchars( $_SERVER['PHP_SELF'] ); ?>" method="post">
                <div class="form-group">
                    <label for="login-username" class="sr-only">Username</label>
                    <input type="text" class="form-control" id="login-username" placeholder="username" name="username">
                </div>
                <div class="form-group">
                    <label for="login-password" class="sr-only">Password</label>
                    <input type="password" class="form-control" id="login-password" placeholder="password" name="password">
                </div>
                <button type="submit" class="btn btn-default" name="login">Login!</button>
            </form>
            <br>
            <br>
        </div>
        <div class="col-md-2"></div>
    </div>
</div><br>
<br>
<br>
<?php include('includes/footer.php'); ?>
 
    