prepared selection shows blank page

I just set up the prepared query selection but it seems like it does not work.. It shows blank page instead of the content it should show..where is problem?

<?php 

        $servername = "";
        $username = "";
        $password = "";
        $dbname = "";

        // Create connection
        $conn = new mysqli($servername, $username, $password, $dbname);
        // Check connection
        if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
}

        $stmt = $mysqli->prepare('SELECT configured FROM members WHERE username = ?');
        $stmt->bind_param('s', $username);

        $stmt->execute();
        $stmt->bind_result($username);

        while ($stmt->fetch()) {

                                if($row['configured'] == ""){
        if (isset($_SESSION['user_id'])) {  


?>

With this code I want to check if user has configured his settings and so if yes, then if he is logged in. But the page shows nothing even though I have there everything correct after that code I posted...

Solution

You're using $conn to connect with, then $mysqli in your prepare statement.

This

$stmt = $mysqli->prepare

Which should read as

$stmt = $conn->prepare

Also make sure you've started the session.

http://php.net/manual/en/function.session-start.php

Check for errors:

http://php.net/manual/en/function.error-reporting.php

and you have 3 missing closing braces in your posted code.

I see you're using $username = ""; in your DB connection and then using the same variable to bind with.

Add error reporting to the top of your file(s) which will help find errors.

<?php 
error_reporting(E_ALL);
ini_set('display_errors', 1);

// rest of your code

Sidenote: Error reporting should only be done in staging, and never production.