I create a table member with 8 fields, with idMember as primaryKey. Two among these fields is the field's date_of_birth and date_back that have same type, date.
But when I insert data into it, appears an error like this -> ORA-01843 not a valid month.
Previously when I didn't include a date field again, successfully. However when I include it, writing error ORA-01843 not a valid month.

I give the insert command like this:
insert into member values ​​('M102019', 'Adhe Nurcahya',.., to_date ('28-May-1992 ',' DD-MON-YYYY'),..., .. , to_date ('12-dec-2011 ',' DD-MON-YYYY '));

Anyone know why is this possible?
I'm confused, is there because in a record to_date there should be no more than 1??
Thank's..