Getting Error in Retun method in php while calling wcf service

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PHP

WCFServices

Dear all,
I am new to web services and also Php,
Here i am trying to consume the Wcf service from php(wamp server)

this is my php code

<?php

try{
require_once ('lib/nusoap.php');
  $client = new SoapClient("http://localhost:51732/Service1.svc?wsdl");

$params = array('value' => '10');

// Call web service PassMember methordd
 $webService = $client-> GetData($parms);
 $wsResult = $webService->GetDataResult();

 print_r($wsResult);

       } catch (Exception $e) {
       echo 'Caught exception:',  $e->getMessage(), "\n";
}
?>

this is my method in service
-------------------------------

namespace First
{
    // NOTE: You can use the "Rename" command on the "Refactor" menu to change the class name "Service1" in code, svc and config file together.
    public class Service1 : IService1
    {
        public string GetData(int value)
        {
            return string.Format("You entered: {0}", value);
        }

        public CompositeType GetDataUsingDataContract(CompositeType composite)
        {
            if (composite == null)
            {
                throw new ArgumentNullException("composite");
            }
            if (composite.BoolValue)
            {
                composite.StringValue += "Suffix";
            }
            return composite;
        }
    }
}

but i got the error like this

Fatal error: Call to undefined method stdClass::GetDataResult() in C:\wamp\www\first.php on line 14


So help me to solve this

thanks in advance