title: jquery ajax doesn't fire
body: <p>I am trying to call a server-side function using Jquery ajax, it doesn't work, I get no error. what can be the problem ? is there a set of rules to make sure my $ajax will work?</p>
  
  <p>//HTML </p>
  
  <pre><code> &lt;asp:DropDownList ID="DDL" runat="server"&gt;
                    &lt;asp:ListItem&gt;aaa&lt;/asp:ListItem&gt;
                      &lt;asp:ListItem&gt;bbb&lt;/asp:ListItem&gt;
                  &lt;/asp:DropDownList&gt;
  </code></pre>
  
  <p>//JS</p>
  
  <pre><code> $(document).ready(function () {
              $("#DDL").change(function () {                             
                  $.ajax({
                      type: "POST",
                      url: "signToCity.aspx/getStreets",
                      contentType: "application/json; charset=utf-8"              
                  });
  
              });
          });
  </code></pre>
  
  <p>//Serverside</p>
  
  <pre><code>  [WebMethod]
          public static void getStreets()
          {                       
           string test="no return:just checking by breakpoint if function is working."
  
          }
  </code></pre>