using sequence in a trigger

I want to use a sequence (met_id_seq) for a unique id (met_id) on a table. I'd like to have an insert trigger take care of that column for me...

create or replace trigger ml_metlab_trg

   before insert or update or delete on ml_metlab

      referencing new as new old as old
      for each row
      begin
         if inserting then
            :new.met_id := met_id_seq.nextval;
         end if;


     :


     :

But I get an error when creating the trigger. PLS-00357: Table,View Or Sequence reference 'MET_ID_SEQ.NEXTVAL' not allowed in this context

what am I missing?
Thanks,
Cary

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Before you buy. Received on Thu Oct 21 1999 - 17:21:15 CDT