Jquery Multiple ajax call

I have a listed navigation with letters and i am trying to call the actors and directors from different json files when the user clicked a letter. I used 2 ajax calls to get the data from actor.php and director.php. It works fine on my local machine, but only the first one works on server. How can i make each ajax calls working?

$(document).ready(function(){
    $('.letters').click( function()开发者_开发问答{
         var letter=$(this).html();

     $.ajax({
       url: 'actor.php?harf='+letter,
       dataType: 'json',
       success: function(JSON) 
                 {  //some code   }
               }); 


     $.ajax({
       url: 'director.php?harf='+letter,
       dataType: 'json',
       success: function(JSON) 
              {  // some code     }
     }); });  });

What happens if you do this:

$.ajax({
   url: 'actor.php?harf='+letter,
   dataType: 'json',
   success: function(JSON) {  
     //some code   
     $.ajax({
       url: 'director.php?harf='+letter,
       dataType: 'json',
       success: function(JSON) {
         // some code
       }
     });
   });
});

Piling up 2 ajax invocations back-to-back is not something I would risk.

it loads when i load director.php?harf=xxx from web browser. just the second ajax call doesnt work when i try to get 2 json file with 2 ajax call.

        $.ajax({
            "type": "POST",
            "dataType": 'json',
            "contentType": "application/json; charset=utf-8",
            "url": "../webmethods.aspx/UpdateNextFollowUpForMultipleInvoice",
            "data": "{'strIds':'" + strIds + "','dtNextFollowUp':'" + dtNextFollowUp + "'}",
            "success": function () {


            }
        });