Problem with trigger...

Hi,
I have the following problem :

I have 2 tables : T-Alumni  and T-AlumniB (exact copy of Alumni, except 3 extra columns : user, date, time)
On events 'update' and 'delete' in table Alumni, I want to copy the old row to AlumniB (as a backuptable) and add the username, date and time.

So I created a function :

CREATE FUNCTION trigfunc_add_alumni() RETURNS opaque AS '
begin
        insert into T-Alumni-B values (old.Id_Person, old.Member, old.Payed, old.Nr, old.Alumninr, old.Acyear, old.Styear);
        return NULL;
end;
'  LANGUAGE 'plpgsql';

Then I wanted to create a trigger using this function with the properties :

Table                   T-Alumni
Executes              AFTER
Event                   UPDATE, DELETE
For each              ROW
Function               trigfunc_add_alumni()

Then I get the error :

An error has occurred in pgAfdmin II:frmTrigger.cmdOK_Click : Number 5
Description : Invalid procedure call or argument

Can someone tell me what i'm doing wrong? Or is there another better solution for this problem?!
Thanks!!

Joepie Platteau.