Get a Invoice - PHP Toolkit

....
$transactionSearch  = new nsComplexObject("TransactionSearch");
$transactionSearchBasic = new nsComplexObject("TransactionSearchBasic");

$transactionSearchBasic->setFields(array(
                                "type" => array( "operator"=>"anyOf",
    "searchValue"=>"_invoice")));

$transactionSearchBasic->setFields(array(
                                "internalId" => array( "operator" => "anyOf",                                                                                       "searchValue"=> array('internalId' => 373))));
// invoice internalId 373 is correct

$transactionSearch->setFields(array("fulfillingTransactionJoin" => $transactionSearchBasic));

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

$result = $searchResponse->totalRecords;
....

Why returned as result 0, when the result is 1 ?

Thanks,
Leandro.