I recently installed BackupPC on my Ubuntu 10.04 LTS web server. I did this by entering 'sudo apt-get install backuppc'. Initially I couldn't get the backuppc web interface to work. Going to http://192.168.0.1/backuppc in a web browser only gave a '404 Not Found' error.
I tracked down the reason for this to me having failed to explicitly selected 'Apache2' as the BackupPC web server. During installation a page something like this had been presented:
Select web server [ ] Apache2 <ok>
I had just hit <enter> assuming that 'Apache2' was the default (there were no other alternatives after all). What I should have done was hit the spacebar to select 'Apache2' and then hit <enter>.
I fixed the problem by completely removing BackupPC ('sudo apt-get purge backuppc') and then reinstalling ('sudo apt-get install backuppc') taking care to hit the spacebar at the appropriate point.
The lack of clear instructions on the above installation page might be regarded as a bug in the BackupPC installation process.
It turns out that I had an almost identical problem a year and half ago when installing PhpMyAdmin.