I can't get sky reflection on my glass windows

I used glossy instead of glass and lowered the roughness. It’s okay now.

I am doing a tutorial here: https://www.youtube.com/watch?v=fFLtCi6yWnA&list=UUG8AxMVa6eutIGxrdnDxWpQ I can’t get the windows to reflect. When I duplicated the building the duplicates would reflect, but the original wouldn’t. I deleted the interior floors or the original thinking that was what was causing the original building not to reflect, but it still doesn’t reflect. Can someone tell me what I am doing wrong?

http://i1130.photobucket.com/albums/m539/Blanco111/help3_zpsb2e82180.png

Blend file: http://www.pasteall.org/blend/31970