PHP4 SOAP Request problem logging in to salesforce.com

Hi, Using PHP4/Pear/SOAP with Apache/Linux, I am having trouble with a login request to salesforce.com that I do not understand. Instead of username and password appearing in the request, there is: <ns4:login xsi:nil="true"/> Taking an open source example - php-client (http://sourceforge.net/project/showfiles.php?group_id=96634&package_id=104202) - (almost) out of the box, with a minor modification to use a wsdl file, the relevant code goes like this: File login.php: require_once("../SalesforceClient.php"); $client = new SalesforceClient(); $result = $client->login($_REQUEST['username'],$_REQUEST['password']); if (PEAR::isError($result)) { $errors = "Error: " . $result->getMessage() . "\n"; } else { // success! } File SalesforceClient.php: require_once("WebService_SforceService_Soap.php"); class SalesforceClient extends WebService_SforceService_Soap { var $sessionId; function SalesforceClient($sessionId = null) { ... $this->WebService_SforceService_Soap(); ... } ... } File WebService_SforceService_Soap.php: require_once 'SOAP/Client.php'; class WebService_SforceService_Soap extends SOAP_Client { function WebService_SforceService_Soap() {

     $wsdl_url = "http://my/url/for/sforce_partner.wsdl";
     $this->SOAP_Client($wsdl_url , true);

} function &login($username, $password) {

       $login =& new SOAP_Value('{urn:partner.soap.sforce.com}login',false,$v=array("username"=>$username, "password"=>$password));
       return $this->call("login",
                       $v = array('login'=>$login),
                       array('namespace'=>'urn:partner.soap.sforce.com',
                           'soapaction'=>'',
                           'style'=>'document',
                           'use'=>'literal' ));

} ... I have a valid salesforce.com developer login, and I am using the partner API. The wsdl file was downloaded from salesforce.com. Here is the actual SOAP request: <?xml version="1.0" encoding="UTF-8"?> <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:ns4="urn:partner.soap.sforce.com" SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"> <SOAP-ENV:Header> <ns4:SessionHeader SOAP-ENV:actor="http://schemas.xmlsoap.org/soap/actor/next" SOAP-ENV:mustUnderstand="0"> <sessionId xsi:nil="true"/></ns4:SessionHeader> <ns4:CallOptions SOAP-ENV:actor="http://schemas.xmlsoap.org/soap/actor/next" SOAP-ENV:mustUnderstand="0"> <client xsi:type="xsd:string">phpClient/1.0</client></ns4:CallOptions> </SOAP-ENV:Header> <SOAP-ENV:Body> <ns4:login xsi:nil="true"/> </SOAP-ENV:Body> </SOAP-ENV:Envelope> A print_r of the login object before the call shows the values: login=Array ( [login] => soap_value Object

       (
           [value] => Array
               (
                   [username] => [my valid username]
                   [password] => [my valid password]
               )

           [name] => login
           [type] =>            [namespace] => urn:partner.soap.sforce.com

... } Can you help me discover why parameters username and password do not appear in the request? Many thanks. Colin Goldberg