Problème formulaire php et mysql.

<form name="APform" action="http://payment.allopass.com/acte/access.apu" method="post" style="text-align:center;clear:both">
    <input type="hidden" name="ids" value="monids" /> <!-- J'y ai mis mon ids -->
    <input type="hidden" name="idd" value="monidd" /> <!-- J'y ai mis mon idd -->
    <input type="hidden" name="data" value="true" /> 
    <input type="text" name="Pseudo" size="8" />
    <input type="text" name="code[]" size="8" />
    <input type="submit" value=" Entrer " />
</form>

<?php
if(isset($_GET['data']) AND $_GET['data'] == 'true'){
//Reportage erreures php
error_reporting(E_ALL);
//Infos Database
$dbhost = '****';
$dbuser = '*******';
$dbpass = '*****';
$dbname = '*******';
$dbtable = 'iConomy';
//Connexion à la base
$conn = mysql_connect ($dbhost, $dbuser, $dbpass) or die ('Error: ' . mysql_error());
mysql_select_db($dbname) or die(mysql_error()) ;
$player = $_POST['Pseudo'];
$query = "SELECT * FROM iConomy WHERE username='".$player."'"; 
$result = mysql_query($query, $conn) or die($query . " - " . mysql_error());
$row = mysql_fetch_row($result);
mysql_query("UPDATE iConomy SET balance=balance+500 WHERE id=".$row[0]);
//Déconnexion
mysql_close();
echo '<script language="Javascript">
<!--
document.location.replace("http://minesword.myriapulse.com");
// -->
</script>';
}else{
	echo "Tricheur";
}
?>

Notice: Undefined index: Pseudo in /var/www/site/minesword.myriapulse.com/allopo.php on line 12