partitioned index <str> in area <str> is empty

  Explanation:  A null dbkey was found as the root dbkey  of  this
  partition  of  a  B-tree index.  It is assumed that there are no
  records in this partition, and hence, the root dbkey is null.

  User Action:  If you know there are records in  this  partition,
  the  index  is corrupt, and you can rebuild the index.  If there
  are no records in the index,  however,  this  is  not  an  error
  condition.