[Plugin: NextGEN Gallery] Next Gen Gallery not downloading

Help, ANYBODY. When I try to install Nex Gen Gallery, I get this message: Destination folder already exists. /hermes/bosweb/web247/b2474/ipg.cornerstonepdcom/wp-content/plugins/nextgen-gallery/

What do I need to do to make this work?

Thanks,

http://wordpress.org/extend/plugins/nextgen-gallery/