INSERT/UPDATE in views fail silently

Hello,

on my linux-systems a write access to views fails without any
error message:

hans=> create table demo (i integer);
CREATE
hans=> create view demoview as select * from demo;
CREATE
hans=> insert into demoview values (5);
INSERT 151142 1
hans=> select * from demo;
i
-
(0 rows)

Does Postgres not support insert/update on views?
Why do I get a 'INSERT' answer from postgres when no data
is inserted?

I'm using Postgres 7.0 and 6.5.3 on two different Linux systems.

Thanks,
Hans