captcha script werkt niet

<?php
session_start();

$randomnr = rand(1000, 9999);
$_SESSION['randomnr2'] = md5($randomnr);


$im = imagecreatetruecolor(100, 38);


$white = imagecolorallocate($im, 255, 255, 255);
$grey = imagecolorallocate($im, 128, 128, 128);
$black = imagecolorallocate($im, 0, 0, 0);


imagefilledrectangle($im, 0, 0, 200, 35, $black);


$font = 'font.ttf';


imagettftext($im, 35, 0, 22, 24, $grey, $font, $randomnr);


imagettftext($im, 35, 0, 15, 26, $white, $font, $randomnr);


header("Expires: Wed, 1 Jan 1997 00:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");


header ("Content-type: image/gif");
imagegif($im);
imagedestroy($im);
?>

<?php
session_start();
 
$randomnr = rand(1000, 9999);
$_SESSION['randomnr2'] = md5($randomnr);
 
 
$im = imagecreatetruecolor(100, 38);
 
 
$white = imagecolorallocate($im, 255, 255, 255);
$grey = imagecolorallocate($im, 128, 128, 128);
$black = imagecolorallocate($im, 0, 0, 0);
 
 
imagefilledrectangle($im, 0, 0, 200, 35, $black);
 
 
$font = 'font.ttf';
 
 
imagettftext($im, 35, 0, 22, 24, $grey, $font, $randomnr);
 
 
imagettftext($im, 35, 0, 15, 26, $white, $font, $randomnr);
 
 
header("Expires: Wed, 1 Jan 1997 00:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
 
 
header ("Content-type: image/gif");
imagegif($im);
imagedestroy($im);
?>

<?php
phpinfo();
?>

<?php
phpinfo();
?>