BlockUI Ajax loading wrong moment - ajax

Question

I know there's other post about this. but there's no answer.
Situation, I have an ajax command. It take time because I have somes things to get.
I want to include a loading between the execution of the ajax.
I want to use jquery BlockUI because its simple and good looking.
But I dont know why the visual effect not working until ajax load the entire data(like when "success" begin).
I try multiple way but not working.
here's my last code :
function from http://www.codeproject.com/Articles/382390/An-Example-to-Use-jQuery-Global-AJAX-Event-Handler
var AjaxGlobalHandler = {
Initiate: function(options) {
$.ajaxSetup({ cache: false });
// Ajax events fire in following order
$(document).ajaxStart(function() {
$.blockUI({
message: options.AjaxWait.AjaxWaitMessage,
css: options.AjaxWait.AjaxWaitMessageCss
});
}).ajaxSend(function(e, xhr, opts) {
}).ajaxError(function(e, xhr, opts) {
if (options.SessionOut.StatusCode == xhr.status) {
document.location.replace(options.SessionOut.RedirectUrl);
return;
}
$.colorbox({ html: options.AjaxErrorMessage });
}).ajaxSuccess(function(e, xhr, opts) {
}).ajaxComplete(function(e, xhr, opts) {
}).ajaxStop(function() {
$.unblockUI();
});
}
};
call ready
var options = {
AjaxWait: {
AjaxWaitMessage: '<h1 class="ui-overlay-loading-content"><img class="ui-overlay-loading-image" src="_inc/img/loading3circle1.gif" />Chargement des données ...</h1>',
AjaxWaitMessageCss: { backgroundColor: '#ffffff' }
},
AjaxErrorMessage: "<h6>Erreur!/h6>"
};
AjaxGlobalHandler.Initiate(options);
call execution
$.ajax({
type: "POST",
url: location.href.split('/').pop() + "?action=" + actionName + "&recherche=" + recherche,
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(response) {
FillDataGridOnSuccess(response, gridId, dataTypeName);
},
error: function(xhr, ajaxOptions, thrownError) {
alert("xhr.status : " + xhr.status);
alert("thrownError : " + thrownError);
}
});
I try also
var ajaxSettings = function(options) {
return $.extend(
{
beforeSubmit: function() {
//beforeSend: function() {
$.blockUI({ overlayCSS: { backgroundColor: '#ffffff' },
message: '<h1 class="ui-overlay-loading-content"><img class="ui-overlay-loading-image" src="_inc/img/loading3circle1.gif" />Chargement des données ...</h1>'
});
},
complete: function() {
$.unblockUI();
}
},
options
);
};
Every test that I did end with a loading who seems to only appear on ajaxSuccess.
I know there's sample on official blockUI site http://jquery.malsup.com/block/#demos
and they working there, but I cant on my own. did anybody see why?
tank you