Salve a tutti, ho inserito questo in una select

codice:
(CASE
				WHEN ( (TRUNC(SS.START_DATE) BETWEEN TRUNC(:fromdate) AND TRUNC(:todate)) AND (TRUNC(SS.END_DATE) BETWEEN TRUNC(:fromdate) AND TRUNC(:todate)) ) THEN TRUNC(SS.START_DATE) /*esterno */
				WHEN ( (TRUNC(:fromdate) BETWEEN TRUNC(SS.START_DATE) AND TRUNC(SS.END_DATE)) AND (TRUNC(:todate)  BETWEEN TRUNC(SS.START_DATE) AND TRUNC(SS.END_DATE)) ) THEN TRUNC(:fromdate) /* centrale */
				WHEN ( TRUNC(:todate) BETWEEN TRUNC(SS.START_DATE) AND TRUNC(SS.END_DATE) ) THEN TRUNC(SS.START_DATE) /* sinistra */
				WHEN ( TRUNC(:fromdate) BETWEEN TRUNC(SS.START_DATE) AND TRUNC(SS.END_DATE) ) THEN TRUNC(:fromdate) /*destra */
				ELSE TRUNC(SS.END_DATE) END) DAY,
ma sto avendo l'errore ORA-30083: è stato trovato un errore di sintassi nell'espressione dei valori per l'intervallo

A cosa può essere dovuto?