include

salut tous le monde,

j'ai un problemes c'est que quand je mais ca ca marche pas. ouest l'erreur svp


include 'http:///a.php?id='.$id1;
include 'http:///a.php?id='.$id2;
include 'http:///a.php?id='.$id3;
include 'http:///a.php?id='.$id4;

merci d'avance

ah non non c'est pas a cause des include
Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started a.php on line 2

voici le code ou il ya l'erreur

session_start();
$_SESSION['login'] = $login;
$_SESSION['pass'] = $data['password'];
$_SESSION['mail'] = $dat['mail'];
echo '<SCRIPT LANGUAGE="JavaScript">document.location.href="a.php" </SCRIPT>';

if (isset($_GET['5'])) {
//include 'em/membres.php';
session_start();
if(!isset($_SESSION['login'])) {
echo '<SCRIPT LANGUAGE="JavaScript">document.location.href="membre.php?1" </SCRIPT>';
}
else{
echo '<p>login ',$_SESSION['login'],'</p>';
echo '<a href="membre.php?1&action=deconnexion">Déconnexion</a>';
}
}

?>

<?include 'pr/2.php'?>

meme  avbec tous ca il ya cette erreur 

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /pr/1.php:12) in /membres.php on line 2