Search Customer Record, Custom Field

Hi,

I'm having issues with search customer record through ItemSearchBasic, i'm trying to search customer with a double custom field as my search value,

Here is my code.

$customerSearchParam = new nsComplexObject('SearchDoubleCustomField');
$customerSearchParam->setFields(array('searchValue' => '' ,'operator' => 'equalTo', 'internalId' => 'custentity1'));
$searchItemFields = array('customFieldList' => array($customerSearchParam));
$customerSearchBasic = new nsComplexObject("CustomerSearchBasic");
$customerSearchBasic->setFields($searchItemFields);

$searchResponse = $myNSclient->search($customerSearchBasic);


here is my soap request:
<SOAP-ENV:Envelope xmlns:ns3="urn:messages_2011_2.platform.webservices.netsuite.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="urn:core_2011_2.platform.webservices.netsuite.com" xmlns:ns2="urn:common_2011_2.platform.webservices.netsuite.com">