You don't have permission to access /otrs/installer.pl on this server

Hello, I tried to install OTRS 1.2.4 on a SuSE Linux 9.2 . When I want to run the setup on http://localhost/otrs/installer.pl I get the error message: "You don't have permission to access /otrs/installer.pl on this server. Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request." I checked the error log of apache2 and it says: "client denied by server configuration: /opt/otrs/bin/cgi-bin/index.pl" What can I do? What/where do I have to change something? Thanks! Regards, Ivan