ORACLE - MERGE Abfrage mit Denkfehler?

MERGE INTO zeitreihe d
USING ( WITH zr4901 AS
      (
      SELECT zr_mobj_id, zr_wert_a, zr_datum,
        Lead ( zr_datum ,1, SYSDATE ) OVER ( PARTITION BY zr_mobj_id ORDER BY zr_mobj_id, zr_datum ) 
        AS datum_next
        FROM zeitreihe
        WHERE zr_zrt_id=4901
        ORDER BY zr_mobj_id, zr_datum
        )
        SELECT zr4900.zr_mobj_id, zr4900.zr_datum,
          (zr4900.zr_wert_a + zr4901.zr_wert_a - BITAND ( zr4900.zr_wert_a, zr4901.zr_wert_a)) erg , 4902
          FROM zeitreihe zr4900, zr4901
          WHERE zr4900.zr_zrt_id = 4900
          AND zr4900.zr_mobj_id (+) = zr4901.zr_mobj_id
          AND (zr.4900.zr_datum > zr4901.zr_datum AND zr4900 <= zr4901.datum_next)
        ) s
ON (d.zr_mobj_id= s.zr4900.zr_mobj_id AND d.zr_datum= s4900.zr_datum AND d.zr_zrt_id = 4902)
WHEN MATCHED THEN UPDATE SET d.zr_wert_a = s.erg
WHEN NOT MATCHED THEN INSERT (d.zr_mobj_id, d.zr_datum, d.zr_wert_a, d.zr_zrt_id)
VALUES (s.zr4900.zr_mobj_id, s.zr4900.zr_datum, s.erg, 4902);