can I use sequence in trigger ?

Hy everybody
I tried to fire a trigger before insert on a table to add a reference number to each row.
Therefore I used a sequence that works fine, but not within the trigger. It says 'SEQ_REFNO_EIN.NEXTVAL not allowed in this context'. Heres the trigger:

create or replace trigger trg_refno_ein
before insert on einnahmen
for each row
begin

                :new.refno :=seq_refno_ein.nextval;
end;
/

Is it just a simple mistake or can't I use a sequence that way ? ciao

        Ronald Received on Thu Dec 28 2000 - 14:47:33 CST