Hi, I'm a noob with SOAP and am having some problems setting the header. Here's my code below:

<?php
//include nusoap
require_once ("nusoap/lib/nusoap.php");

//set up parameters
$param = array('AccountNumber' =>'N...1','UserName' => 'N...i','Password' => '2...r');
//set up serverpath
$serverpath = 'https://myserver/soap/V200611.ASMX?WSDL';
//declare new soapclient, for cvent, the true is absolutely essential, without it you will throw a SOAPAction error
$client = new soapclient($serverpath, true);
//make the call
$loginResult = $client->call('Login',$param);
print_r($loginResult);
//set soap headers
$CventServerURL = ($loginResult['LoginResult']['!ServerURL']);
$CventSessionHeader = ($loginResult['LoginResult']['!CventSessionHeader']);
$ClientSessionHeader ="<SessionHeader xmlns=\"" . $CventServerURL . "\"><SessionID>" .$CventSessionHeader. "</SessionID></SessionHeader>" ;
$client->setHeaders($ClientSessionHeader);

?>

I can login successfully but I then have to set the session id and url in the header and keep getting this error:

[!ErrorMessage] => ) ) Array ( [faultcode] => q0:CV10107 [faultstring] => UNKNOWN_HEADER_VALUE [faultactor] => http://myserver/soap/V200611.ASMX )

Any help would be appreciated