mainsite can see added gallery name in gallery management.
mainsite url: http://domainname/
wordpress installed direcotry: -root/blog/
Nextgen gallery can create gallery in main site and access properly.
Nextgen gallery can created gallery in subsite, but didn't show up in manage gallery.
the added gallery folder went to -root/blog/, and didn't go to
no DB record was created for added gallery for subsite.