sequence in trigger

I need an example of using a sequence in a trigger. I tried this, but I get a compiler error saying that the sequence cannot be referrenced in this context.

CREATE TRIGGER CUSTOMER_BEF_INS_KEY_ID

        BEFORE INSERT
        ON JIM.CUSTOMER
        FOR EACH ROW
        BEGIN
             :new.KEY_ID:=CUSTOMER_SEQUENCE.NextVal;
        END;

Thanks

--
Jim Poe
<jpoe_at_fulcrumit.com>
Fulcrum InteTech, Inc.