Definitely not Lower Austria.
Crni Lug is in today's Croatia -- which was part of the Austro-Hungarian Empire. Please use Croatia-L mailing list:
http://www.rootsweb.com/~hrvwgw/mailing.htmand/or:
http://cgi.rootsweb.com/~genbbs/genbbs.cgi/Croatia/GeneralNote: there are other Crni Lugs in Serbia and in Bosnia and Herzegovina too. See:
http://www.jewishgen.org/shtetlseeker/loctown.htm