Apps How can I Removing the titlebar without error

[Developer1515]

I need to remove the titlebar on my android application.

I used:

android:theme="@android:style=theme.dark.Notitlebar.FullScreen"

And that's in my android manifest file under the <application>

And when I launch the app I get the error "Unfortunately, app has stoped working" or something like that.

Any words of advise?