the  RSE  in  a  START_SEGMENTED_STRING  does  not  reference  a
  segmented string

  Explanation:   The   START_SEGMENTED_STRING   record   selection
  expression refers to a real record stream instead of a segmented
  string  field.   START_SEGMENTED_STRING  may   refer   only   to
  segmented strings.

  User Action:  Use a segmented string field in the RSE portion of
  the START_SEGMENTED_STRING command.