Erreur connection php

Bonjour,

j ai une erreur pour la connection des eleves sur un site que je dois rendre dans 1 petite semaine (benevolat) la connection fonctionne en local mais sur le net j ai l erreur suivante d afficher avec le formulaire
si vous pouviez m aider celà me soulagerai d un grand poids car il me reste encore beaucoup de travail

merci pour votre reponse et pour votre ecoute
Anne Marie

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /mnt/105/sdc/f/2/amarie.gazonnaud/index.php:4) in /mnt/105/sdc/f/2/amarie.gazonnaud/connectE.php on line 40

voici le script de ma page

<?php require_once('Connections/connection.php'); ?>
<?php
if (!function_exists("GetSQLValueString")) {
function GetSQLValueString($theValue, $theType, $theDefinedValue = "", $theNotDefinedValue = "")
{
$theValue = get_magic_quotes_gpc() ? stripslashes($theValue) : $theValue;

$theValue = function_exists("mysql_real_escape_string") ? mysql_real_escape_string($theValue) : mysql_escape_string($theValue);

switch ($theType) {
case "text":
$theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
break;
case "long":
case "int":
$theValue = ($theValue != "") ? intval($theValue) : "NULL";
break;
case "double":
$theValue = ($theValue != "") ? "'" . doubleval($theValue) . "'" : "NULL";
break;
case "date":
$theValue = ($theValue != "") ? "'" . $theValue . "'" : "NULL";
break;
case "defined":
$theValue = ($theValue != "") ? $theDefinedValue : $theNotDefinedValue;
break;
}
return $theValue;
}
}

mysql_select_db($database_connection, $connection);
$query_Recordset1 = "SELECT nom, pass FROM eleves";
$Recordset1 = mysql_query($query_Recordset1, $connection) or die(mysql_error());
$row_Recordset1 = mysql_fetch_assoc($Recordset1);
$totalRows_Recordset1 = mysql_num_rows($Recordset1);
?><?php
// *** Validate request to login to this site.
if (!isset($_SESSION)) {
session_start();
}

$loginFormAction = $_SERVER['PHP_SELF'];
if (isset($_GET['accesscheck'])) {
$_SESSION['PrevUrl'] = $_GET['accesscheck'];
}

if (isset($_POST['nom'])) {
$loginUsername=$_POST['nom'];
$password=$_POST['pass'];
$MM_fldUserAuthorization = "";
$MM_redirectLoginSuccess = "indexEleves.php";
$MM_redirectLoginFailed = "connectE.php";
$MM_redirecttoReferrer = false;
mysql_select_db($database_connection, $connection);

$LoginRS__query=sprintf("SELECT nom, pass FROM eleves WHERE nom=%s AND pass=%s",
GetSQLValueString($loginUsername, "text"), GetSQLValueString($password, "text"));

$LoginRS = mysql_query($LoginRS__query, $connection) or die(mysql_error());
$loginFoundUser = mysql_num_rows($LoginRS);
if ($loginFoundUser) {
$loginStrGroup = "";

//declare two session variables and assign them
$_SESSION['MM_Username'] = $loginUsername;
$_SESSION['MM_UserGroup'] = $loginStrGroup;

if (isset($_SESSION['PrevUrl']) && false) {
$MM_redirectLoginSuccess = $_SESSION['PrevUrl'];
}
header("Location: " . $MM_redirectLoginSuccess );
}
else {
header("Location: ". $MM_redirectLoginFailed );
}
}
?>
<form ACTION="<?php echo $loginFormAction; ?>" name="form1" method="POST">
<label>Nom
<input type="text" name="nom" id="nom">
</label>
<p>
<label>Pass
<input type="password" name="pass" id="pass">
</label>
</p>
<p>
<label>
<input type="submit" name="Envoyer" id="Envoyer" value="Envoyer">
</label>
<label>
<input type="submit" name="Effacer" id="Effacer" value="Effacer" />
</label>
<?php
mysql_free_result($Recordset1);
?>
<br>
</p>
</form>