Estoy tratando de escribir un cliente para estoservicio web

Utiliza una autenticación de dos capas (una en el encabezado de solicitud y activada para el acceso a datos en el servidor), lo que significa que necesito pasarla en el encabezado. Esto es lo que intenté hacer:

class ChannelAdvisorAuth 
{ 
    public $DeveloperKey; 
    public $Password; 

    public function __construct($key, $pass) 
    { 
        $this->DeveloperKey = $key; 
        $this->Password = $pass; 
    } 
} 

$devKey      = "user"; 
$password    = "pass"; 

$soapArr = array(
    "trace"=>true,
    "exceptions"=>true,
);

$url         = "http://soalive.grimaldiwebservices.it/framework/JourneyManager?wsdl"; 
$client     = new SoapClient($url, $soapArr); 
echo "client created!"; 
print_r($client -> __getFunctions());
$auth         = new ChannelAdvisorAuth($devKey, $password); 
$header     = new SoapHeader($url, "APICredentials", $auth, false); 

$in0 = array( 
    "in0" => array( 
        "user"        => "user", 
        "password"    => "pass",
        "message-id"  => "",
        "status"   => array("error-code" => "", "error-desc" => ""),
        "shiplist"   => array("code-ship" => "", "desc-ship" => "")
    ));


echo "athenticated"; 

$result = $client->__soapCall("getShips", $in0); //line 41

Tengo este error:

    Fatal error: Uncaught SoapFault exception: [env:Server] XPath expression 
failed to execute. An error occurs while processing the XPath expression; the 
expression is 
ora:parseEscapedXML(bpws:getVariableData('OnMessage_getShips_InputVariable','par
ameters','/ns1:getShips/ns1:in0')). The XPath expression failed to execute; the
 reason was: Start of root element expected.. Check the detailed root cause 
described in the exception message text and verify that the XPath query is 
correct. in C:\Program Files (x86)\xampp\htdocs\Test\index.php:41 Stack trace: 
#0 C:\Program Files (x86)\xampp\htdocs\Test\index.php(41): SoapClient-
>__soapCall('getShips', Array) #1 {main} thrown in C:\Program Files 
(x86)\xampp\htdocs\Test\index.php on line 41

Lo admito, esta no es realmente mi taza de té, ¿alguien puede explicar lo que está pasando?

¿Puedo llamar manualmente a este servicio web? usando jabón UI tal vez?

Este es el cliente generado en soapUI, el mismo error al ejecutar:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:gfw="http://gfw.services.grimaldilines.com">
   <soapenv:Header>
   <soapenv:Body>
      <gfw:getShips>
         <gfw:in0>?</gfw:in0>
      </gfw:getShips>
   </soapenv:Body>
</soapenv:Envelope>