showPageLoadingMsg not showing when i remove alert

showPageLoadingMsg not showing when i remove alert


when i add alert along with showPageLoadingMsg, both are getting loaded. but when i remove alert showPageLoadingMsg showing. could any reply on this?
$.mobile.showPageLoadingMsg();
alert('loading');


code

$(document).on('pagecreate', '#filterPage', function(){ 
//$.mobile.showPageLoadingMsg("a","Loading...");
currentDate=06/18/2013&filterID=-1";
  var currentDate = {};  
  currentDate['currentDate'] = '06/18/2013';
  currentDate['filterID'] = '-1';
$.ajax({
           type: "POST",
            url: 'data/GetComboBoxValues.xml',
            dataType: "xml",
async : true,
error: function(){
alert("error, while hitting the action class");
},
            success: xmlParser
        });


 
});


 $(document).ajaxStart(function () {   
 
$.mobile.showPageLoadingMsg();
alert('loading');
}).ajaxComplete(function () {        
$.mobile.hidePageLoadingMsg();
});