trigger fails in Oracle
===

Any idea on why this trigger will not create:

here is my table:

    desc comments;
    
    comment_id not null number(300)
    post_id not null number(300)
    user_id not null number(300)
    message not null varchar2(2500)
    timestamp not null timestamp(6)

I've created a sequence

    create sequence comment_seq 
    start with 1 
    increment by 1 
    nomaxvalue; 


And this is the trigger I'm trying to create:


    create trigger comment_trigger
    before insert on comments
    for each row
    begin
    select comment_seq.nextval into :new.comment_id from dual;
    end;
    /


I'm getting the error

"ERROR AT LINE 2:
ORA-06552: PL/SQL Complication unit analysis terminated
ORA-06553: PLS-320: The declaration of the type of this expression is incomplete or malformed"
