If you're building packages with pbuilder sometimes you might hit something like the following errors which cause the build to fail because the dependencies can't be found.
Err http://archive.ubuntu.com/ubuntu/ precise-updates/main devscripts i386 2.11.6ubuntu1.2 404 Not Found [IP: 126.96.36.199 80] Err http://archive.ubuntu.com/ubuntu/ precise-updates/main openssl i386 1.0.1-4ubuntu5.2 404 Not Found [IP: 188.8.131.52 80]
The cause is the pbuilder image being out of date and some dep packages are no longer present becuase they've been superceded by more recent versions. The good news is the fix is really simple just run:
Which will update your pbuilder image and from there the dependency installation should work just fine.