jspdf download button doesn't do anything when clicked. in android cordova

i make an android app with cordova and angularjs. I have made download pdf button and it works fine on my laptop. but when compiled to android, my button doesn't do anything when clicked. i have added plugin cordova plugin add org.apache.cordova.file

i followed tutorial here http://www.tricedesigns.com/2014/01/08/generating-pdf-inside-of-phonegap-apps/ and here my code.

           $scope.exportPDF = function(){       
                    alert("tes");
                    //FIRST GENERATE THE PDF DOCUMENT
                    console.log("generating pdf...");
                    var doc = new jsPDF();

                    doc.text(20, 20, 'HELLO!');

                    doc.setFont("courier");
                    doc.setFontType("normal");
                    doc.text(20, 30, 'This is a PDF document generated using JSPDF.');
                    doc.text(20, 50, 'YES, Inside of PhoneGap!');

                    var pdfOutput = doc.output();
                    console.log( pdfOutput );

                    //NEXT SAVE IT TO THE DEVICE'S LOCAL FILE SYSTEM
                    console.log("file system...");
                    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function(fileSystem) {

                       console.log(fileSystem.name);
                       console.log(fileSystem.root.name);
                       console.log(fileSystem.root.fullPath);

                       fileSystem.root.getFile("test.pdf", {create: true}, function(entry) {
                          var fileEntry = entry;
                          console.log(entry);

                          entry.createWriter(function(writer) {
                             writer.onwrite = function(evt) {
                             console.log("write success");
                          };

                          console.log("writing to file");
                             writer.write( pdfOutput );
                          }, function(error) {
                             console.log(error);
                          });

                       }, function(error){
                          console.log(error);
                       });
                    },
                    function(event){
                     console.log( evt.target.error.code );
                    });
}

the alert is worked, but my pdf still not work. any suggestion?