xsi:type or maybe SoapVar misuse?

I'm pretty sure what I'm up against now is a namespace issue and/or a  
misunderstanding of how to use SoapVar.

 From the NetSuite docs, the request should look something like:

<soapenv:Body>
<search xmlns="urn:messages_2_5.platform.webservices.netsuite.com">
<searchRecord xsi:type="ns1:ContactSearch"  
xmlns:ns1="urn:relationships_2_5.lists.webservices.netsuite.com">
	<ns1:customerJoin xsi:type="ns2:CustomerSearchBasic"  
xmlns:ns2="urn:common_2_5.platform.webservices.netsuite.com">
		<ns2:internalId operator="anyOf"  
xsi:type="ns3:SearchMultiSelectField"   
xmlns:ns3="urn:core_2_5.platform.webservices.netsuite.com">
			<ns3:searchValue internalId="1" type="customer"  
xsi:type="ns3:RecordRef"/ >
		</ns2:internalId>
	</ns1:customerJoin>
</searchRecord>
</search>
</soapenv:Body>

But what I'm actually requesting looks like:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/ 
envelope/"  
xmlns:ns1="urn:messages_2_5.platform.webservices.netsuite.com">
<SOAP-ENV:Body>
<ns1:search>
	<customerJoin>
	 	<internalId>
			<operator>anyOf</operator>
			<searchValue>1</searchValue>
		</internalId>
	</customerJoin>
</ns1:search>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

The code to do so looks something along the lines of:

$ssr = new SOAPContactSearch();
$ssr->customerJoin = new SOAPCustomerSearchBasic();
$ssr->customerJoin->internalId = new SOAPSearchMultiSelectField();
$ssr->customerJoin->internalId->operator =  
SOAPSearchMultiSelectFieldOperator::$anyOf;
$ssr->customerJoin->internalId->searchValue = "1";
$param = new SoapVar($ssr, SOAP_ENC_OBJECT);
$search_result = $netsuite_service->search($param); //  
$netsuite_service extends SoapClient, naturally

The generated error is:

org.xml.sax.SAXException: Unable to marshall between XML and Castor  
Objects :unable to find FieldDescriptor for 'internalId' in  
ClassDescriptor of SearchRecord

I assume I'm using SoapVar() incorrectly or this is a namespace issue  
(like I'm not specifying xsi:type)???

Thanks for any help!

~ Andrew