title: WebMethod with optional parameter doesn't work in client side
body: <p>I write a webmethod with optional parameter.</p>
  
  <pre><code>[WebMethod]
    public void EmailSend(string from, string to, string cc = null, string bcc = null, string replyToList = null, string subject = null, string body = null, bool isBodyHtml = false , string[] attachmentNames = null, byte[][] attachmentContents = null)
      {
       .....
      }
  </code></pre>
  
  <p>I call this method in client side application</p>
  
  <pre><code> EmailServiceManagement.EmailService es = new EmailServiceManagement.EmailService();
   es.EmailSend(from, to,null,null,null,subject,body,true,attName,att); //this works
  </code></pre>
  
  <p>but</p>
  
  <pre><code>es.EmailSend(from,to); // this isn't working. According to c# optional parameter syntax it must work.
  </code></pre>
  
  <p>What am I doing wrong?</p>