Postgres permissions for www-data

Hello,

I'm using Zope 2.3.2, PostgreSQL 7.1.2 and psycopg 0.99.2.
On a Debian system Zope is running as user www-data.

I created this user using
   > createuser www-data

Moreover I made sure in psql:

   web=# select usename from pg_user;
    usename
   ----------
    postgres
    tillea
    www-data
   (3 rows)
   web=# grant all on testtable to "web-data" ;
   CHANGE

which seems to be OK so far.

Opening a database connection from Zope works well.  I used the
connection string:

    dbname=web

Unfortunately if I want to test the connection using

    select * from testtable ;

I get

Error Type: ProgrammingError
Error Value: ERROR: testtable: Permission denied. select * from testtable ;


Looking at /var/log/postgres.log I see the following entries:

2001-06-19 14:05:24 [22300]  DEBUG:  connection: host=[local] user=www-data database=web
2001-06-19 14:05:43 [22300]  ERROR:  testtable: Permission denied.

I also studied the archive:

   http://fts.postgresql.org/db/mw/msg.html?mid=53327
   http://fts.postgresql.org/db/mw/msg.html?mid=30785

deal with this problem but I found no solution for this problem.
According to this mails I tried to remap the username using pg_ident.conf
but nothing helped (remapping doesn't seem to work because the log-entry
did not change).

Moreover if I try to use a connection string with any username (different
from www-data or also www-data) and password even the connection itself
fails.

Kind regards

         Andreas.