Trigger problem...

Hi,
I hope that you could help we with my problem. I already posted it on
the mailing lists, but nobody answered it to the point.
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 (This error I always get when I want to create a
trigger based on a function (also with predefined functions) :

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

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

P.S.S. I have versions
Pgadmin : 1.3.82-Dev
Postgresql : 7.2.1
ODBC-driver : 7.2.4

Joepie Platteau.