Header fejlen er

Warning: Cannot modify header information - headers already sent by (output started at /home/wwwsites/ho/jpr/tilmeldmignu.php:1) in /home/wwwsites/ho/jpr/tilmeldmignu.php on line 108

Hvad betyder dette? og hvordan løser jeg problemet??

$headers = "From: JPR2003 Staff <nomail@nomail>\n";
$headers .= "X-Sender: <nomail@nomail>\n";
$headers .= "X-Mailer: PHP\n";
$headers .= "X-Priority: (Highest)\n";
$headers .= "Return-Path: <jpr2003@pcproblemer.dk>\n";
$headers .= "Content-Type: text/html; charset=iso-8859-1\n";
$headers .= "MIME-Version: 1.0\n";   
$headers .= "Bcc: g@g.dk\r\n";

mail("$email", $subject, $message, $headers);


linie 108: header("Location: http://www.houensodde.dk/jpr");

?>