formidable parse callback not be called and no error - node.js

Question

I have problem when I use formidable parse function. In my project, I use httpsys (not build-in http module) to create server (for port sharing), and then I send a post request with multipart form data(including string and zip file). Then I want to use formidable to parse request body. But parse function callback does not be called. There is no error. I do not use Express application, but I use Express Router to route my requests. I already use error handler to catch error, but it never be called (form.on('error', function(err) { console.log(err); });). Anyone has same problem? Please help me out, thanks in advance.
// main.js
var router = express.Router();
router.use(function (req, res, next) {
for (var i in req.headers) {
req.headers[i] = querystring.unescape(req.headers[i]);
req.headers[i] = req.headers[i].replace(/\+/g, "");
}
next();
});
//router.use(bodyParser());
router.post('/TestServer/' + 'TestRequest', function(req, res) {
testRequestHandler.execute(req, res);
});
var server = require('httpsys').http().createServer(router);
var port = '80'; // or other port
var listeningPort = 'http://localhost:' + port + '/TestServer/';
server.listen(listeningPort );
// In testRequestHandler
var execute = function(req, res) {
var form = new Formidable.IncomingForm();
form.uploadDir = uploadDir.getPath();
form.encoding = Constants.ENCODING_UTF8;
form.on('file', function(name, file) {console.log('file='+file);});
form.on('error', function(err) { console.log(err); }); // never be called
form.on('aborted', function() { console.log('Aborted'); });
form.parse(req, function(err, fields, files) {
//todo test code
console.log( "parse finished" );
});
}