php 对接java的soap 以xml传参报“未将对象引用设置到对象的实例” 有大神帮忙看看么

php代码是这样的
try {
ini_set("soap.wsdl_cache_enabled", "0");
header("content-type:text/html;charset=utf-8");

$url = 'http://221.179.7.250/NGADCInfcText/NGADCServicesForEC.svc?wsdl';


$client = new \SoapClient($url,array( 'soap_version'=>SOAP_1_1, 'trace'=>1, 'classmap' => array('Person' => "Person", 'PersonList' => "PersonList")));
$client->soap_defencoding = 'utf-8';
$client->decode_utf8 = false;
$client->xml_encoding = 'utf-8';

$arr = array(
'OrigDomain' => 'NGEC',
'BIPCode' => 'EC0001',
'BIPVer' => 'V1.0',
'TransIDO' => 'NG'.rand(11,99).date('YmdHis',time()).rand(1,9),
'Areacode' => 'GZ',
'ECCode' => '200000426',
'ECUserName' => 'yangjie@2002219673',
'ECUserPwd' => md5('a3spmr3c'),
'ProcessTime'=> date('YmdHis',time()),
);
// $xml = new \SimpleXMLElement ( '<NGEC></NGEC>' );
// $this->_data2xml ( $xml, $arr );
// $str = $xml->asXML ();
$xml = $this->array2xml($arr);
// //xml转为对像
$dom = new \domDocument;
$dom->loadXML($str);
$obj = simplexml_import_dom($dom);



// echo '<pre>';
// print_r($client->__getFunctions()) ;
// print_r($client->__getTypes()) ;


dump($obj);
$res =$client-> __Call('AdcServices',array($obj));


var_dump($res);die;

} catch (SOAPFault $e) {
print $e;
}