Error : ORA-01861: literal does not match format string

This is my query :

WITH details AS (

SELECT ppl.person_number,

  ppl.person_id ,

  pet.base_element_name,

  pee.effective_start_date start_date,

  TO_DATE(peev.screen_entry_value, 'YYYY-MM-DD HH24:MI:SS') seniority_date,

  '5 years' renewal_cycle,

  ADD_MONTHS(TO_DATE(peev.screen_entry_value, 'YYYY-MM-DD HH24:MI:SS'), 60) anniversary_date,

  grd.name grade,

  flv.meaning worker_category,

  ppnf.display_name name,

  ple.name legal_employer

  

FROM  per_person_secured_list_v ppl,

  pay_element_types_f pet,

  pay_element_entries_f pee,

  pay_input_values_f piv,

  pay_element_entry_values_f peev,

  per_assignment_secured_list_v paf,