I am new to this concept, this is my first project implementing the optimization concept with (Bundling & minification)
Just i am trying to test with simple js
Your bundling is working, problem is you css are not working when bundled.
Change your style sheet bundle name to this:
bundles.Add(new StyleBundle("~/css/allcss").Include("~/css/master.css"));
This should solve your problem.
P.S. if you keep your css files in multiple folders, then create a bundle for each folder. You can use the IncludeFolder method to make your job easier.