Php SoapClient与ssl

I am trying to use php soapclient to use this wsdl https://ecbq-test.fin.em2.oraclecloud.com/finArTrxnsCreditMemos/CreditMemoService?wsdl

I allowed php_openssl.dll in php.ini

then then I saved certification file from browser and add it next to my php code

$url="https://ecbq-test.fin.em2.oraclecloud.com/finArTrxnsCreditMemos/CreditMemoService?wsdl";
$params = array (
'local_cert'=>  $local_cert,
'trace' => true,
'exceptions' => true
 );
try
{
    $client = new SoapClient($url,$params );
var_dump($client->test());
}catch (SoapFault $f)
{
var_dump($f);
}

an code did not work

SOAP-ERROR: Parsing WSDL: Couldn't load from 'https://ecbq-test.fin.em2.oraclecloud.com/finArTrxnsCreditMemos/CreditMemoService?wsdl' : failed to load external entity "https://ecbq-test.fin.em2.oraclecloud.com/finArTrxnsCreditMemos/CreditMemoService?wsdl

can any one help me please ?? thanks