design website Could not find schema information for element

why was error Could not find schema information for the element 'http://schemas.microsoft.com/.NetConfiguration/v2.0:configuration' ? you see attach file http://www.mediafire.com/file/jimpgxd88zzfnab/BookShopOnline.rar/file and see file pictures http://www.mediafire.com/view/67di18r0ea4dadg/errorwebconfig.jpg/file