I use appcompat v22.1.0 in my App and use Toolbar. Everything was fine when I use Theme.AppCompat.Light.NoActionBar. When I start implement AlertDialog
Basically your Activity is using Toolbar (which replaces Action Bar) so you need to use style for the Activity that has no Action Bar like Theme.AppCompat.Light.NoActionBar.
If you have your own style for dialog then you need to inherit the proper AppCompat theme.
AlertDialog.Builder builder = new AlertDialog.Builder(new ContextThemeWrapper(this, R.style.myDialog));