Problem med header functionen

Hej alle.....

Jeg har et script der ser sådan ud

<?
session_start();
?>

<?
include ("config.php");
mysql_connect($host,$user,$pass);
mysql_select_db($db);
$query = mysql_query("SELECT * FROM community WHERE navn='$s_navn' AND password='$s_password'") or print mysql_error();
while($r = mysql_fetch_array($query)) {
$id = $r["id"];
$navn = $r["navn"];
$password = $r["password"];
$email = $r["email"];
$alder = $r["alder"];
$theme = $r["theme"];
$date = $r["date"];
}

$SQL = "insert into beskedtilanders
  (navn, overskrift, besked, fra, date)
  values ('$til', '$overskrift', '$besked', '$navn', now())";
mysql_query($SQL) or die(mysql_error());
header("location:sebeskeder.php");
?>

den udskriver så en fejl der ser således ud:

Warning: Cannot add header information - headers already sent by (output started at /var/www/hotels/1go/hejungklub/html/Bryrup/insertbesked.php:5) in /var/www/hotels/1go/hejungklub/html/Bryrup/insertbesked.php on line 24

What is WRONG????? plz hjælp