trigger failure

[Quoted] what is false in this trigger. SQLPlus fehler: Warning: Trigger created with compilation errors.

the trigger:

create or replace trigger tr_test

    before insert on switch
    referencing old as old new as new
    for each row
    begin

            :new.switchnr := select seq_test.nextval from dual;     end;

the sequence:

    create sequence seq_test increment by 1

       start with 10
       maxvalue 99
       minvalue 10
       cache 20
       order

I work with oracle server 7.3.3.3 (sqlplus) on solaris 2.5.1.

regards

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Paul C. Kreis                           Informatiker Ascom 
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