MACOSX10.8 doesn't recognize L.O. dmg disk image

I tried three times to download, but got this message. What do I do now? It works on my older version of MAC.

Mountain Lion added some security features that sometimes make it hard to install LibreOffice - "LibreOffice.app (v3.6.2.2) is damaged and can't be opened..." has additional info ( http://www.italovignoli.org/2012/08/libreoffice-and-mountain-lion-macos-x-10-8/ )