problems using mod_auth_pgsql

Happy new year to everybody!

I want to set up a web server, which is connected to a database. The
content of the db should only be available for authorized users.
My configuration is:
Suse Linux 7.2
Apache 1.3.20
mod_auth_pgsql 0.9.11
PostgreSQL 7.1.3

I created the .htaccess file and made the corresponding adjustments in
the httpd.conf:
Content of .htaccess:
AuthName "PostgreSQL Authenticator"
AuthType basic
Auth_PG_host localhost
Auth_PG_port 5432
Auth_PG_user postgres
Auth_PG_database authdb
Auth_PG_pwd_table user_authentication
Auth_PG_uid_field auth_user
Auth_PG_pwd_field auth_pwd
<LIMIT GET POST>
        require valid-user
</LIMIT>

Entry in httpd.conf:
<Directory /path_to_mydir>
    AllowOverride AuthConfig
</Directory>

Everything works well without these modifications. But if I place the
.htaccess file into the directory of my web project I can find
following entry in Apaches error_log:
[Sat Dec 29 19:44:55 2001] [error] (2)No such file or directory:
access to /test/index.html filed for MY_IP, reason: PG user andreas:
password mismatch
I can see the login window but I can’t authorize with the user
information stored in my database.

If I send the following sql query manually to PostgreSQL it responds
with the correct pwd:
select auth_pwd from user_authentication where auth_user='andreas';
(should be the same query like the one from mod_auth_pgsql)

It would be great if somebody could point me in the right direction.
Does anyone use the authentication with mod_auth_pgsql successfully?

Thank you in advance.
Salut!
Andreas