failing to start roundcube webmail after setup

[atux]

hi. i am trying to setup roundcube to allow users to check their emails.
i am doing the setup
http://domain.com/roundcubemail/installer/ and i follow the setup wizard. no errors at all. then it says to remove the install by issuing rm -r /var/www/roundcubemail/installer.
after that i am not able to access roundcube at all.
i am typing http://domain.com/roundcubemail/ and it opens a white page (not even a wrong page).
is there a way to fix this issue? what am i missing?
i will appreciate any help. the system is running in debian 6.

[SKaero]

What is in the RoundCube error log?