I am trying to add an option menu in actionbar to my existing app but it is not working. If I create a new project with \"hello world\" default app I can see the button in a
Have you tried to set the app theme to a theme that supports the ActionBar, like Theme.Holo.Light?
ActionBar
Theme.Holo.Light
Also, in your Activity you can try getActionBar().show();.
Activity
getActionBar().show();