APEX

I am attempting to add a bulk loader to my apex application (apex 4.1) using the standard bulk loader add-on that comes with apex.

I am finding that I am getting date conversion errors.

If I change the column to a varchar2 I can run a to_date on all the data loaded and this works fine.  (to_date(result_datetime,'DD-MM-YYYY HH24:MI:SS'))

If I put the to_date on the values in a before trigger I still get the error.  ie :new.result_datetime:= to_date(trim(:new.result_datetime),'DD-MM-YYYY HH24:MI:SS');

Is apex trying to do the string to date conversion and if so how can I set the date format that the string is in?