IntelliJ Ultimate 14 find usages not working

Question

I am using Intellij IDEA 14 Ultimate. When I search find usages, in find view there is a info like

Searching for usages in project files\" and doesn\'

Answer 1

If it doesn't solve by File -> Invalidate Caches / Restart then make sure your 'src' folder is marked as 'Sources' in project structure.