I've setup Redmine 2.1 on my Debian Squeeze server following this Tutorial HowTo configure Redmine for advanced git integration (I tried to use the grack path). Redmine server is running properly, but I have a problem granting users access to git repositories.

When I try to clone a repository it says:

error: The requested URL returned error: 500 while accessing

The apache error.log shows this entry:

[Fri Sep 28 15:50:56 2012] [crit] [client xx.xx.xx.xx] configuration error: couldn't check user. Check your authn provider!: /repo.git/info/refs

It also asks me for user and password when cloning, but it shouldn't if I understand the tutorial right.

I'm using the Redmine authentication module:

<VirtualHost *:80>
    ServerName my.server.at
    DocumentRoot "/var/www/my.server.at/public" 

    PerlLoadModule Apache::Redmine

    <Directory "/var/www/my.server.at/public">
        Options None
        AllowOverride None
        Order allow,deny
        Allow from all
    </Directory>

        SetEnv REMOTE_USER=$REDIRECT_REMOTE_USER" 
        SetEnv GIT_PROJECT_ROOT /var/git/my.server.at/
        SetEnv GIT_HTTP_EXPORT_ALL
        ScriptAlias /git/ /usr/lib/git-core/git-http-backend

    <Location />
        Order allow,deny
        Allow from all

        AuthType Basic
        AuthName Git
        Require valid-user

        AuthBasicAuthoritative Off
        AuthUserFile /dev/null
        AuthGroupFile /dev/null

        PerlAccessHandler Apache::Authn::Redmine::access_handler
        PerlAuthenHandler Apache::Authn::Redmine::authen_handler

        RedmineDSN "DBI:mysql:database=redmine;host=localhost" 

        RedmineDbUser "user" 
        RedmineDbPass "password" 
        RedmineGitSmartHttp yes
    </Location>
</VirtualHost>

Can someone help me please and explain the error and what I can do to solve my problem?