value block is not valid

  Explanation:  This warning message is returned if the caller has
  specified  the  VALBLK flag in the flags argument to the service
  to request locks.  Note that  the  lock  has  been  successfully
  granted despite the return of this warning message.

  User Action:  This error message indicates a possible  error  in
  the    locking   protocols.    Contact   your   Oracle   support
  representative for assistance.