Create the group by saying
-`G V my.virtual.newsgroup<RET>nnvirtual<RET>^rec\.aquaria\.*<RET>'
+`G m my.virtual.newsgroup<RET>nnvirtual<RET>^rec\.aquaria\.*<RET>'
This will create the group "nnvirtual:my.virtual.newsgroup", which
will collect all articles from all the groups in the "rec.aquaria"