If you once generate views with root view, go to layout and add new views, root view will be missed next time when you regenerate new views. Like in this example for fragment
// old generated views
oldView1= (View) view.findViewById(R.id.oldView1);
oldView2= (View) view.findViewById(R.id.oldView2);
// new generated view
newView1= (View) findViewById(R.id.newView1);`
If you once generate views with root view, go to layout and add new views, root view will be missed next time when you regenerate new views. Like in this example for fragment