I'm trying to send this:
Code:
<?xml version="1.0" encoding="utf-8"?>
<Request version="1.0" xmlns="http://europay.smart2pay.com/message">
<Action>INSERT_PAYIN</Action> <MID>F520156B-5E64-447F-B0B2-C638FA101C6F</MID> <PaymentMethod>mercadopago</PaymentMethod> <IPAddress>127.0.0.1</IPAddress> <Hash>F83525BC77811EC24FF10E50383BB5ED</Hash>
<Details>
 <MTID>123456789</MTID>
 <Amount>100</Amount>
 <Currency>REA</Currency> <SuccessURL>http://www.smart2pay.com/success.html</SuccessURL>    <FailureURL>http://www.smart2pay.com/failure.html</FailureURL> <CancelURL>http://www.smart2pay.com/cancel.html</CancelURL>   <ProcessingURL>http://www.smart2pay.com/processing.html</ProcessingURL> <Shipping Amount="50" CostMode="DS" />
 <Language>pt-BR</Language> <Description>payment</Description>
 <CustomerName FirstName="John" LastName="Doe" /> <CustomerEmail>john.doe@test.com</CustomerEmail>
    </Details>
</Request>
like this:

Code:
$client = new SoapClient("https://europaytest.smart2pay.com/MerchantService.asmx?wsdl");
$response = $client->__doRequest($xml, "https://europaytest.smart2pay.com/MerchantService.asmx", "SubmitRequest", 1.1);
...but it just doesn't work saying "Server did not recognize the value of HTTP Header"

Any ideas?