[fw-mvc] problem in zend_soap_client

hi guys

my code is  :

$soapZarinPal = new Zend_Soap_Client("http://www.zarinpal.com/WebserviceGateway/wsdl", array('encoding'=>'UTF-8'));
            $configOBJ = new Config();
            $configData = $configOBJ->getConfigs();
            $siteURLcallBack = $configData[0]['siteurl']."/account/verifypayment";
          
            $res = $soapZarinPal->PaymentRequest('mypinnumberin  zarinpal.com', '1000', $siteURLcallBack, "a");
            $this->_redirect("https://www.zarinpal.com/users/pay_invoice/" .$res);

and it throws this exception :

SoapFault: Operation '' is not defined in the WSDL for this service

thrown in C:\Users\Sina Miandashti\Desktop\xampplite\xampplite\htdocs\vando\library\Zend\Soap\Client.php on line 1118

Call Stack

1. SoapClient->__soapCall()
   in C:\Users\Sina Miandashti\Desktop\xampplite\xampplite\htdocs\vando\library\Zend\Soap\Client.php on line 1118

--
________________
Sincerely
Sina Miandashti
MuSicBasE.ir & InvisionPower.ir Admin