Android Question Android theme not found

I put this line in my manifest to adjust theme for Lolipop and all was working fine until I started to get the following error upon compilation.

"AndroidManifest.xml:18: error: Error: No resource found that matches the given name (at 'theme' with value '@android:style/Theme.Holo')."

My app will not run unless I remove this line.

does anyone know what might have happened? Where is this resource found?

Thanks,
Dan