PHP - ทำ QR CODE ค่าไม่ดึงอ่ะครับ PHP QR Code encoder

<center>

<?php
$pis = 1234;
?>
<?php   
/*
 * PHP QR Code encoder
 *
 * Exemplatory usage
 *
 * PHP QR Code is distributed under LGPL 3
 * Copyright (C) 2010 Dominik Dzienia <deltalab at poczta dot fm>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */
    
    /*echo "<h1>PHP QR Code</h1><hr/>";*/
    
    //set it to writable location, a place for temp generated PNG files
    $PNG_TEMP_DIR = dirname(__FILE__).DIRECTORY_SEPARATOR.'temp'.DIRECTORY_SEPARATOR;
    
    //html PNG location prefix
    $PNG_WEB_DIR = 'temp/';

    include "qrlib.php";    
    
    //ofcourse we need rights to create temp dir
    if (!file_exists($PNG_TEMP_DIR))
        mkdir($PNG_TEMP_DIR);
    
    
    $filename = $PNG_TEMP_DIR.'test.png';
    
    //processing form input
    //remember to sanitize user input in real-life solution !!!
    $errorCorrectionLevel = 'H';
    if (isset($_REQUEST['level']) && in_array($_REQUEST['level'], array('L','M','Q','H')))
        $errorCorrectionLevel = $_REQUEST['level'];    

    $matrixPointSize = 4;
    if (isset($_REQUEST['size']))
        $matrixPointSize = min(max((int)$_REQUEST['size'], 1), 10);


    if (isset($_REQUEST['data'])) { 
    
        //it's very important!
        if (trim($_REQUEST['data']) == '')
            die('data cannot be empty! <a href="?">back</a>');
            
        // user data
        $filename = $PNG_TEMP_DIR.''.md5($_REQUEST['data'].'|'.$errorCorrectionLevel.'|'.$matrixPointSize).'.png';
        QRcode::png($_REQUEST[''], $filename, $errorCorrectionLevel, $matrixPointSize, 2);    
        
    } else {    
       
        //default data
        /*echo 'You can provide data in GET parameter: <a href="?data=like_that">like that</a><hr/>'; */   
     
		QRcode::png ('$pic' ,$filename, $errorCorrectionLevel, $matrixPointSize, 2);
       /* QRcode::png('$test');*/
    } 	
    //display generated file
    echo '<img src="'.$PNG_WEB_DIR.basename($filename).'" /><hr/>';