ContactList_UpdateInsert returning Fatal error: Uncaught SoapFault exception

I am creating a script to capture our customers email and then generate a password after they place an order.  This will then be placed into the BC crm along with an external database to create an account on another system.  I have everything working up to the point of inserting a new password for the user.  Considering I have multiple calls using this same structure that are working correctly such as Case_Retreive and Contact_RetreiveByEntityID, I am a bit confused by the error.

Everytime I try to call the ContactList_UpdateInsert I am getting this error:

Fatal error: Uncaught SoapFault exception: [soap:Server] Server was unable to process request. ---> ERROR: A server error has occured. in /home/content/28/9663728/html/clientList.php:71 Stack trace: #0 /home/content/28/9663728/html/clientList.php(71): SoapClient->__soapCall('ContactList_Upd...', Array) #1 {main} thrown in /home/content/28/9663728/html/clientList.php on line 71

My code snippet:

$passArray = array(

     'username' => 'myadminusername',

     'password' => 'myadminpassword',

     'siteId' => '123456',

     'externalId' => '555555');

$client = new SoapClient('https://coburncreative02.worldsecuresystems.com/catalystwebservice/catalystcrmwebservice.a smx?WSDL');

$passResult = $client->__soapCall('ContactList_UpdateInsert', array('parameters' => $passArray));

My next question is how you go about (with php) to insert a variable into the password field of the crm. My guess is something like this:

$passResult[password] = 'newpass';