truncate problem

I've just tried to do a truncate on a table, but get this error:

ORA-02266: unique/primary keys in table referenced by enabled foreign keys

The table was created like this:

create table headline
(

        id number(10) primary key,
        headline varchar2(200),
        url varchar2(200),
        grabtime number(15),
        comments varchar2(200),
        lang number(4),

        constraint fk_headline_lang
                foreign key (lang)
                references language (id)

Is the constraint causing the problem? No row in the headline table has any value in the lang column.

thanks,

• Kev