I have installed the server according to the instructions in "The Perfect Server", including Roundcube. However I get an error page when I go to /webmail and also to /roundcube How can I debug what is wrong? Is there a way to just reinstall it? How does IspConfig detect it / work with it? It's not like in the previous version. BTW, I tried a VM from HowToForge with this setup and there /roundcube works, but /webmail not.