Redmine

I have bitnami LAMP stack installed in my ubuntu. Now I have installed redmine on my system which is using the already existing mysql and apache2 following the below document :-

http://www.redmine.org/projects/redmine/wiki/HowTo_Install_Redmine_231_On_Ubuntu_1204_with_git_and_Redmine_Git_Hosting_plugin#HowTo-Install-Redmine-231-On-Ubuntu-1204-clean-installation-with-git-and-Redmine-Git-Hosting-plugin

But I am unable to get the redmine login page. Instead, a page showing index of file is getting displayed. Kindly help me to fix this.