There is a bug in Ubunty Jaunty which cause Trac to have errors.

Attachments do not work, the admin interface for milestones doesn’t work properly - and there may be other issues.

The bug report is at https://bugs.launchpad.net/ubuntu/+source/trac/+bug/369792

And the solution is

I just started on a project that was using trac and subversion but they weren’t integrated. I love the cross referncing trac provides. It can really help explain changesets and show how an issue was resolved.

The steps to add subversion to trac are