does not execute any code in php tag
<p>I do not know PHP programming, and we have an  PHP application in our organization that should be launched. and I have problem with it.
when iIdelete this part of index.php application working properly.
with in this part of code application does not run.
I think the problem is the PHP tag. 
in this tag does not execute any code.</p>

<pre><code>    &lt;?php   session_start();
    if(!isset($_SESSION['initiated'])){
        $_SESSION['initiated']=true;
        session_regenerate_id(true);        
    }
    error_reporting(0);

    include("includes/cn.php");
    include("includes/config.php");
    include("includes/jdf.php");

    include_once ('parts/header.php');

    if(isset($_GET['df'])) {

        $qStr = "set GLOBAL read_only = false";
        $db_conn-&gt;query($_qstr);
        if ($db_conn-&gt;errno) {
            die("Execution failed: ".$db_conn-&gt;errno.": ".$db_conn-&gt;error); 
        }
    }
?&gt;
</code></pre>
