Show prgress bar when export PDF or Excel in Kendo PivotGrid -

i using code show progress bar in kendo pivotgrid when export file:

var item = this.prepareexport(".pdf");     item.chart.setoptions({         pdf: {             allpages: true,             filename: item.filename,             proxyurl: item.url         },         pdfexport: function (e) {             kendo.ui.progress($(e.sender.element), true);             e.promise             .done(function () {                 kendo.ui.progress($(e.sender.element), false);             });         }     });     item.chart.saveaspdf(); 

but code show progress bar in first time export file. question how every click export file, progress bar showed.

p/s: sorry english.