Ho trovato la soluzione:
Devo aggiungere
"lc" => "IT", all Array.
Quindi diventa:
<?php
$url = "https://www.paypal.com/cgi-bin/webscr";
$tax_total = $db->f("order_tax") + $db->f("order_shipping_tax");
$discount_total = $db->f("coupon_discount") + $db->f("order_discount");
$post_variables = Array(
"cmd" => "_xclick",
"business" => PAYPAL_EMAIL,
"receiver_email" => PAYPAL_EMAIL,
"item_name" => $VM_LANG->_PHPSHOP_ORDER_PRINT_PO_NUMBER.": ". $db->f("order_id"),
"order_id" => $db->f("order_id"),
"invoice" => $db->f("order_number"),
"amount" => round( $db->f("order_subtotal")+$tax_total-$discount_total, 2),
"shipping" => sprintf("%.2f", $db->f("order_shipping")),
"currency_code" => $_SESSION['vendor_currency'],
"image_url" => $vendor_image_url,
"return" => SECUREURL ."index.php?option=com_virtuemart&page=checkout.result&order_id=".$db->f("order_id"),
"notify_url" => SECUREURL ."administrator/components/com_virtuemart/notify.php",
"cancel_return" => SECUREURL ."index.php",
"undefined_quantity" => "0",
"lc" => "IT",
"test_ipn" => PAYPAL_DEBUG,
"pal" => "NRUBJXESJTY24",
"no_shipping" => "1",
"no_note" => "1"
);
if( $page == "checkout.thankyou" ) {
$query_string = "?";
foreach( $post_variables as $name => $value ) {
$query_string .= $name. "=" . urlencode($value) ."&";
}
mosRedirect( $url . $query_string );
} else {
echo '<form action="'.$url.'" method="post" target="_blank">';
echo '<input type="image" name="submit" src="http://images.paypal.com/images/x-click-but6.gif" border="0" alt="Make payments with PayPal, it is fast, free, and secure!">';
foreach( $post_variables as $name => $value ) {
echo '<input type="hidden" name="'.$name.'" value="'.$value.'" />';
}
echo '</form>';
}
?>
