invalid structure level in backup file

  Explanation:  The structure level version specified in  a  block
  header  in  the  database  backup file indicates either that the
  backup file was created with a format that is incompatible  with
  this  release  of  Oracle  Rdb  RMU  or  that the backup file is
  corrupt, or that there has been  an  error  reading  the  backup
  file.

  User Action:  Dump the backup file using RMU/DUMP/BACKUP to  see
  if  there  are  any  errors reading the backup file.  Repeat the
  RMU/RESTORE command after moving the backup file to a  different
  device  to see if the problem is related to a particular device.
  If the problem still occurs repeat the backup to  create  a  new
  backup  file  and  then retry the restore.  If the problem still
  occurs contact Oracle Rdb support.