Проблема с функцией eval

$tpl->compile('main');
eval(' ?' . '>' . $tpl->result['main'] . '<' . '? ');
$tpl->global_clear();
?>

unset($_SESSION['Donatd']);
unset($_SESSION['Donatd2']);

if ($_GET['page'] == 'login')
{
    if (!$_SESSION['Name'] and !$_SESSION['Server'])
    {
        $tpl->set('{content}', $tpl->sub_load_template('login.tpl'));
        if ($_POST['name'] and $_POST['password'] and $_POST['server'])

<?php
error_reporting(-1);
ini_set('display_errors', 1);
header('Content-Type: text/plain; charset=utf-8');
 
$txt = <<<'TXT'
<blabla>
<trulala>
<?php
        flush();
    setcookie('test','test');
 
?>
</blablа>
TXT;
 
eval('?>'.$txt );

eval('ob_start(); ?>'.$txt .'<?php ob_end_flush(); ');

$txt = <<<'TXT'
<blabla>
<trulala>
<?php
    flush();
    eval("  setcookie('test','test');" );
 
?>
</blablа>
TXT;
 
eval(' ?'.'>'.$txt);
/*
Warning:  Cannot modify header information - headers already sent
 in <b>C:\T\home\www\index.php(21) :
 eval()'d code(5) :
 eval()'d code</b> on line 1
*/

log_write($tpl->result['main']);
 
function log_write($message)
     {
       $handle=fopen('test.log','a');
       fwrite($handle,print_r($message,true)."\n");
       fclose($handle);
     }