php - PHP での SOAP API 統合: SoapClient エラー

Question

sopaUI で XML を使用すると結果は正常に表示されますが、次の php コードを使用すると結果が空白になり、次のエラーが発生しますFatal error: Uncaught SoapFault exception: [soap:Server] System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.NullReferenceException: Object reference not set to an instance of an object. at Saia.Presentation。パラメータをコメントアウトしても結果に変化がないため、問題は Soap ヘッダーか何かにあると思います。

wsdl ファイルとスキーマを入手した場所へのリンク: http://www.saiasecure.com/webservice/pickup/n_Create.asp

$client = new SoapClient("http://www.saiasecure.com/webservice/pickup/soap.asmx?wsdl",array( 'trace' => 1,
'exceptions' => true,'features' => SOAP_SINGLE_ELEMENT_ARRAYS, ));

$params = array("UserID" => '*******',
        "Password" => '*****',
        "TestMode" => "Y",
        "AccountNumber" => '******',
        "CompanyName" => 'TESTING NAME',
        "Street" => 'TESTING STREET',
        "Box" => 'TESTING BOX',
        "City" => 'LOS ANGELES',
        "State" => 'CA',
        "Zipcode" => '90001',
        "ContactName" => 'TESTING CONTACT',
        "ContactPhone" => '1234567890',
        "PickupDate" => '2013-09-24',
        "ReadyTime" => '13:00:00',
        "CloseTime" => '17:00:00',
        "SpecialInstructions" => 'Nothing',
         "Details" => array("DetailItem" => array("DestinationZipcode" => '70364', "Pieces" => '5', "Package" => 'SK',"Weight" => '100', "Freezable" => 'N') ));
    //print('<pre>');print_r($params);  
$return = $client->Create($params);