使用nusoap发送xml

Question

我的肥皂请求格式应该如下所示

<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>< WsAbcMobileAcctInq xmlns="http://tempuri.org/"><xml_var><HCMSG xmlns="">
<ABC><ABCTRANSID>MOBL</ABCTRANSID></ABC><REF><TXNTYPE>INQ</TXNTYPE><SC_CD>000ACD</SC_CD>
< REFNO>MOBL0000000060018987941MAT</REFNO></REF><FIXPART><TXNDATE>20110105</TXNDATE>
<TXNTIME>11464178</TXNTIME><AGN_CD>000000006001</ AGN_CD ></FIXPART><VARPART>
<AC_NO TYP="N">0000000000008946565</AC_NO>
<IC_NO TYP="N">0008956466546</ IC_NO>
<ID_CD TYP="S">IN</ ID_CD>
</VARPART></HCMSG></xml_var></ WsAbcMobileAcctInq></soap:Body></soap:Envelope>

但问题是我不知道如何使用nusoap。这就是我一直在做的事情：

require_once('lib/nusoap.php');
$client = new nusoap_client('http://domain.my/MobileData/Service.asmx', false);
$params = '<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>< WsAbcMobileAcctInq xmlns="http://tempuri.org/"><xml_var><HCMSG xmlns="">
<ABC><ABCTRANSID>MOBL</ABCTRANSID></ABC><REF><TXNTYPE>INQ</TXNTYPE><SC_CD>000ACD</SC_CD>
< REFNO>MOBL0000000060018987941MAT</REFNO></REF><FIXPART><TXNDATE>20110105</TXNDATE>
<TXNTIME>11464178</TXNTIME><AGN_CD>000000006001</ AGN_CD ></FIXPART><VARPART>
<AC_NO TYP="N">0000000000008946565</AC_NO>
<IC_NO TYP="N">0008956466546</ IC_NO>
<ID_CD TYP="S">IN</ ID_CD>
</VARPART></HCMSG></xml_var></ WsAbcMobileAcctInq></soap:Body></soap:Envelope>';
 $answer = $client->call('WsAbcMobileAcctInq', array('WsAbcMobile' => $params), '', 'http://tempuri.org/WsAbcMobileAcctInq');
 $error = $client->getError();
if ($error){
print_r($client->response);
print_r($client->getDebug());
print_r($client->getError());
die();
}

基本上我得到了这个错误：

HTTP/1.1 500 Internal Server Error Connection: close Date: Thu, 24 Nov 2011 05:47:47 GMT Server: Microsoft-IIS/6.0 X-Powered-By: ASP.NET X-AspNet-Version: 2.0.50727 Cache-Control: private Content-Type: text/xml; charset=utf-8 Content-Length: 441 soap:ServerServer was unable to process request. ---> Object reference not set to an instance of an object

任何线索？