Paypal IPN Script not adding info to the database

Question

Trying to get a script to add a user to a database. But after the script is loaded there is a blank page. Anyone see what I am doing wrong? I am testing it in the pay pal sandbox. I have tried the database code with a form and it works. I was hoping for at least some errors so I could figure out what I am doing wrong.

<?php
// read the post from PayPal system and add 'cmd'
$req = 'cmd=_notify-synch';

$tx_token = $_GET['tx'];
$auth_token = "<your identity token>";
$req .= "&tx=$tx_token&at=$auth_token";

// post back to PayPal system to validate
$header = "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Host: http://www.sandbox.paypal.com\r\n";
// $header .= "Host: http://www.paypal.com\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";

// url for paypal sandbox
$fp = fsockopen ('ssl://www.sandbox.paypal.com', 443, $errno, $errstr, 30);  

// url for payal
// $fp = fsockopen ('www.paypal.com', 80, $errno, $errstr, 30);
// If possible, securely post back to paypal using HTTPS
// Your PHP server will need to be SSL enabled
// $fp = fsockopen ('ssl://www.paypal.com', 443, $errno, $errstr, 30);

if (!$fp) {
  // HTTP ERROR
} else {
fputs ($fp, $header . $req);
// read the body data
$res = '';
$headerdone = false;
while (!feof($fp)) {
  $line = fgets ($fp, 1024);
  if (strcmp($line, "\r\n") == 0) {
    // read the header
    $headerdone = true;
  }
  else if ($headerdone) {
    // header has been read. now read the contents
    $res .= $line;
  }
}

// parse the data
$lines = explode("\n", $res);
$keyarray = array();
if (strcmp ($lines[0], "SUCCESS") == 0) {
  for ($i=1; $i<count($lines);$i++){
    list($key,$val) = explode("=", $lines[$i]);
    $keyarray[urldecode($key)] = urldecode($val);
  }
// PAYMENT VALIDATED & VERIFIED!

echo"Verified!";

     // include mysql connection information
     include 'mysql_info.php';

     // connect to mysql
     $conn = mysqli_connect(DBHOST,DBUSER,DBPASS,DBNAME);

     // Check if the connection failed
     if( !$conn ) {
        die('Failed to connect '.mysqli_connect_error());

     // Hash the password to prevent knowing what it is
     // we use the username as a salt so we can recreate the hash on login
     // using strtolower on the user name so only the password is case sensitive
 $email = $_POST['payer_email'];
 $username = $_POST['os0'];
     $pass = hash('sha256',strtolower($_POST['username']).$_POST['os1']);

    // prepare data for database
     $username = mysqli_real_escape_string($conn,$_POST['username']);
     $email = mysqli_real_escape_string($conn,$_POST['email']);

     // Create the insert query, using real_escape_string to prevent SQL Injection
     $query = sprintf("INSERT INTO `users` (`username`,`email`,`password`) VALUES ('%s','%s','%s')",
                      $username, $email, $pass);

     // Attempt insert the new user
     if( mysqli_query($conn,$query) ) {
        die('You have successfully registered as '.$_POST['username'].'<br /><a href="/login.php">Click here</a> to log in.');
     } else {
        // Insert failed, set error message
        $errors[] = 'Error adding user to database, MySQL said:<br>
           ('.mysqli_errno($conn).') '.mysqli_error($conn).'</span>';
     }

}
}
else if (strcmp ($lines[0], "FAIL") == 0) {
  // log for manual investigation
  echo "Fail!";
}
}
fclose ($fp);

?>