In Oracle Alert SQL expression not Working

Summary:I have created an alert where it needs to be triggered when anyones work schedule got changed.

I have created sql filter in alert section but my alert is taking time to run and fails.

please find below query expression

EXISTS (select 'X' from per_all_people_f papf , per_all_assignments_m paaf, ZMM_SR_SCHEDULES_VL adr1, PER_SCHEDULE_ASSIGNMENTS pa1 where paaf.person_id =papf.person_id and sysdate between papf.effective_start_date and papf.effective_end_date and pa1.resource_id=paaf.assignment_id and sysdate between paaf.effective_start_date and paaf.effective_end_date and paaf.PRIMARY_FLAG='Y' and paaf.assignment_status_type='ACTIVE' and pa1.SCHEDULE_ID = adr1.SCHEDULE_ID aND trunc(pa1.last_update_date) = trunc(sysdate)