Hi I have a problem withi calling WCF Service methods vs Silverlight 3. ` private bool usr_OK = false;

  clientService.CheckUserMailAsync(this.mailTF.Text);


        if (usr_OK == true)
        { isValidationOK = true; }
        else { isValidationOK = false; MessageBox.Show("User already exists.", "User registered succes!", MessageBoxButton.OK); }

` CheckUserMail should change usr_OK parameter. However it runs in other thread and it does not change the usr_OK param before IF block begins. I've tried thread.join byt the application freezed and i do not know what to do else. Please help me...how can i wait for WCF method to return param usr_OK.