Panier Paypal item_name vide

Bonjour à tous,

J'ai un petit soucis (qui me soule depuis quelques jours maintenant) pour la mise en place de mon panier paypal.
Pour faire simple, quand je valide mon formulaire le paramètre "item_name" est vide.

mon formulaire :

        
<form target="paypal" action="https://www.sandbox.paypal.com/us/home" method="post">
<input type="hidden" name="cmd" value="_cart">
<input type="hidden" name="business" value="seller@adresse.fr">
<input type="hidden" name="lc" value="FR">
<input type="hidden" name="item_name" value="badges">
<input type="hidden" name="item_number" value="badge">
<input type="hidden" name="amount" value="4.90">
<input type="hidden" name="currency_code" value="EUR">
<input type="hidden" name="button_subtype" value="products">
<input type="hidden" name="no_note" value="0">
<input type="hidden" name="tax_rate" value="0.000">
<input type="hidden" name="shipping" value="1.50">
<input type="hidden" name="add" value="1">
<input name="return" type="hidden" value="www.adresse.fr/transaction/valide.php" />
          <input name="cancel_return" type="hidden" value="www.adresse.fr/nonvalide.php" />
          <input name="notify_url" type="hidden" value="www.adresse.fr/transaction/validation.php" />
<input type="hidden" name="bn" value="PP-ShopCartBF:btn_cart_LG.gif:NonHostedGuest">
<input type="image" src="https://www.paypalobjects.com/fr_FR/FR/i/btn/btn_cart_LG.gif" border="0" name="submit" alt="PayPal - la solution de paiement en ligne la plus simple et la plus sécurisée !">
<img alt="" border="0" src="https://www.paypalobjects.com/fr_FR/i/scr/pixel.gif" width="1" height="1">
</form>

validation.php

// read the post from PayPal system and add 'cmd'
$req = 'cmd=_notify-validate';

foreach ($_POST as $key => $value) {
$value = urlencode(stripslashes($value));
$req .= "&$key=$value";
}

// post back to PayPal system to validate
$header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";
$fp = fsockopen ('ssl://www.paypal.com', 443, $errno, $errstr, 30);

// assign posted variables to local variables
$item_name = $_POST['item_name'];
$item_number = $_POST['item_number'];
$payment_status = $_POST['payment_status'];
$payment_amount = $_POST['mc_gross'];
$payment_currency = $_POST['mc_currency'];
$txn_id = $_POST['txn_id'];
$receiver_email = $_POST['receiver_email'];
$payer_email = $_POST['payer_email'];

	$texte= 'item name : '.$item_name."\n";
	$texte.= 'item number : '.$item_number."\n";
	$texte.= 'payment status : '.$payment_status."\n";
	$texte.= 'payment_amount : '.$payment_amount."\n";
	$texte.= 'payment_currency : '.$payment_currency."\n";
	$texte.= 'txn_id: '.$txn_id."\n";
	$texte.= 'receiver_email : '.$receiver_email."\n";
	$texte.= 'payer_email : '.$payer_email."\n";
	$texte.= 'id user : '.$id_user."\n";
	
    mail("monadresse@akta.fr",'test', 'item : '.$item_name, $texte);	
[..]

Donc voilà, si vous avez une idée je suis preneur, car je ne sais pas comment faire..

Merci..