[jQuery] $ajax() method does not work on Mozilla and Chrome but it works on IE

Hi,

I have the following servlet that returns:
....
response.setContentType("text/plain;charset=UTF-8");
out.write("{\"XXX\":1}");
...

My Html is

$(document).ready(function(){

$.getJSON("http://localhost:8080/getData",
function(json){
alert("getJSON Server Data->"+json);
});

$("input.dataUpdate").click(function () {
$.ajax({
url: "http://localhost:8080/getData",
success: function(data) {
alert('ajax Data->'+data);
}
});
});
});

Here the $.ajax() does not work neither in Mozilla nor Chrome, but it
works in IE

Can you help me

Thanks in Advance