unknown user "<str>"

  Explanation:  An attempt was made to access information with a
  user name unknown to the database (for example, sending mail to
  the monitor or attempting to execute a database recovery process
  (DBR)) or to access information with a user name unknown to the
  operating system (for example, no record in the UAF file).

  User Action:  Make sure the user name is spelled correctly and
  has been properly identified to either the database or the
  operating system.  Do not attempt to run DBR from DCL; this is
  not allowed, because the system will automatically manage
  database recovery.  Be sure the monitor user name is correctly
  specified.