Calling WebServices using PHP

We are attempting to call a function via webservices using PHP. If the Function in NAV has no parameters but is just returning something, it works.

As soon as there is a parameter the Web Services returns this error:
"Parameter passInHelloWorld in method HelloWorld in service TreeNoWebService is null! "

Here is the php code:
if($Client = new NTLMSoapClient($baseUrl))
{
$value = (string)"HelloWorldValue";
$reponse = @$Client->__call('HelloWorld', array ('passInHelloWorld'=>$value));

die(print_r($response, true));
}

Freddy has a post regarding php but it doesn't inlude a parameter, only a return (http://blogs.msdn.com/freddyk/archive/2 ... m-php.aspx).

Anyone have any thoughts?