express.js: Route Function not called express.js

My express.js configuration looks like this:

//app.js:
var routes = require('./routes/index');
app.use(express.static(path.join(__dirname, '../client/build'), {'index': false}));
app.use('/', routes);

//routes/index.js:
router.get('/', function(req, res) {
 console.log("im never called");
});

My handler is NEVER called (should be called when requesting without path or just '/'), the browser just gets a 303 with Location //, what is wrong here?

Thanks in advance for help!

Try to add module.exports = router; to the end of routes/index.js

Edit:

There is a common practice to put all your static files in one directory (maybe you have done it already) and make all requests to static files start with /public:

app.use('/public', express.static(path.join(__dirname, '../client/build'));

Doing this way

http://yoursite.com/public/some/file.js

will be served with

../client/build/some/file.js

Instead of /public you may choose a path that will not intersect with your router.