Ionic2 fails to create the build folder

Hi there,

i have just created an ionic2 app with sidemenu template & serve it with the ionic serve command. but it show nothing on the the browser except the 404 errors for(angular2-polyfills.js, app.bundle.js and es6-shim.min.js). In-fact it is not creating the build folder.

please suggest.

My ionic version: 2.0.0-beta.6
Node Version: v4.4.4

Thanks