OK, that's clear.
That means function call lookup_ext([Staging_Area.BODIUSER.HOLIDAY_CALENDAR,'PRE_LOAD_CACHE','MAX'], [HOLIDAY_FLAG],['Y'],[CALENDAR_DATE,'=',$G_sysdate])
returns 'Y'.
Or, totally equivalent,
select HOLIDAY_FLAG from BODIUSER.HOLIDAY_CALENDAR where CALENDAR_DATE = $G_sysdate returns null or 'Y'.
Can you check the record in the HOLIDAY_CALENDAR table for the date you submit?