Silverlight Helloworld service

i have service just hellworld in my application

Code:

---

[OperationContract]
        public string HelloWorld()
        {
            return "Helloworld";
        }

---

here is some patch in Reference.cs

Code:

---

  public event System.EventHandler<HelloWorldCompletedEventArgs> HelloWorldCompleted;

---

Code:

---

  public partial class HelloWorldCompletedEventArgs : System.ComponentModel.AsyncCompletedEventArgs
        {

            private object[] results;

            public HelloWorldCompletedEventArgs(object[] results, System.Exception exception, bool cancelled, object userState) :
                base(exception, cancelled, userState)
            {
                this.results = results;
            }
        }

---

and here is the .xmal page code behind

Code:

---

          client.HelloWorldCompleted += new EventHandler<HelloWorldCompletedEventArgs>(Func);
          client.HelloWorldAsync();

---

Code:

---

  void Func(object sender, HelloWorldCompletedEventArgs e)
        {
            string s;
       
         
        }

---

it gives me 2 error

Error 1 The type or namespace name 'HelloWorldCompletedEventArgs' could not be found (are you missing a using directive or an assembly reference?) C:\Users\Iram\Documents\Visual Studio 2008\Projects\SilverlightWithWCFService\SilverlightWithWCFService\MainPage.xaml.cs 30 59 SilverlightWithWCFService


Error 2 'SilverlightWithWCFService.CustomerService.SampleServiceClient' does not contain a definition for 'HelloWorldAsync' and no extension method 'HelloWorldAsync' accepting a first argument of type 'SilverlightWithWCFService.CustomerService.SampleServiceClient' could be found (are you missing a using directive or an assembly reference?) C:\Users\Iram\Documents\Visual Studio 2008\Projects\SilverlightWithWCFService\SilverlightWithWCFService\MainPage.xaml.cs 31 19 SilverlightWithWCFService


so far i did not find nay thing i m missing , so please help me,mean while i m looking into the solution of teh problem