Getting the validation error while running hr_change_start_date_api.update_start_date manually

Hello,

I am trying to update the person effective start date using

hr_change_start_date_api.update_start_date manually, but getting the error

ORA-20001: Person changes exist between the old date and the new date.

Attached the Code:

DECLARE

lc_warn_ee VARCHAR2(2000) := NULL;

lc_error VARCHAR2(2000) := NULL;

BEGIN

HR_UTILITY.SET_TRACE_OPTIONS('TRACE_DEST:DBMS_OUTPUT');

HR_UTILITY.TRACE_ON;

apps.hr_change_start_date_api.update_start_date

(p_validate => FALSE ,

p_person_id =>1256 ,

p_old_start_date => TO_DATE('01-FEB-2015','DD-MON-YYYY') ,

p_new_start_date => TO_DATE('30-APR-2016','DD-MON-YYYY') ,

p_update_type => 'E' ,