SoapHeader with nuSoap

[Jakee]

Hey guys,I am trying to use purorlators webservice with nuSoap, however I keep getting this php error: : Class 'SoapHeader' not found

My code:

<?php

require_once('nusoap.php');

$client = new SoapClient( "EstimatingService.wsdl", 

                            array	(

                                    'trace'			=>	true,

									//Development (dev)

                                    'location'	=>	"https://devwebservices.purolator.com/PWS/V1/Estimating/EstimatingService.asmx",

                                    //Production

									//'location'	=>	"https://webservices.purolator.com/PWS/V1/Estimating/EstimatingService.asmx",

									'uri'				=>	"http://purolator.com/pws/datatypes/v1",

                                    'login'			=>	PRODUCTION_KEY,

                                    'password'	=>	PRODUCTION_PASS

                                  )

                          );

  //Define the SOAP Envelope Headers

  $headers[] = new SoapHeader ( 'http://purolator.com/pws/datatypes/v1',<-----I get the error here

                                'RequestContext', 

                                array (

                                        'Version'           =>  '1.3',

                                        'Language'          =>  'en',

                                        'GroupID'           =>  'xxx',

                                        'RequestReference'  =>  'Rating Example'

                                      )

                              ); 

  //Apply the SOAP Header to your client                            

  $client->__setSoapHeaders($headers);


  return $client; 

And the line I get the error is here :

$headers[] = new SoapHeader ( 'http://purolator.com/pws/datatypes/v1',<-----I get the error here 

So I assume SoapHeaders are not in nuSoap.php . How do I get headers working with nuSoap?