date format and copy command

Using 6.5.3 on SuSE 6.4 and program kpgsql.
Dumped data to a ';' delimited file wherein the date looks like
'1997-12-27'.  The date field may be null.

Created the appropriate table using variously date/datetime/timestamp for
data type, set datestyle to ISO/SQL/others.
The copy command is
    copy tablename from '/usr/.../namefile.txt' using delimiters ';';

The pgsql response is 'bad date format'.
Recommendations, please.

Thanks,
Bill Barnes