ORA-01861: literal does not match format string

I have a view created on Oracle DB 11g with the structure like this:

The column event_dtm is defined as: TO_DATE (b.general_2, 'dd-mm-yyyy hh24:mi:ss') event_dtm (the general_2 allows null)

The column created_dtm is defined as: a.charge_date created_dtm (charge_date is not null column)

I have 2 queries:

The 1st query:

SELECT COUNT(*)

FROM SELFCARE.HCPT_INTEC_USAGE_DETAILS_UAT

WHERE CREATED_DTM BETWEEN TO_DATE('01-10-2018','DD-MM-YYYY') AND TO_DATE('02-10-2018','DD-MM-YYYY');

Result:

The 2nd query:

SELECT COUNT(*)

FROM SELFCARE.HCPT_INTEC_USAGE_DETAILS_UAT