Are you by any chance running the version from the software center?
The latest version is 1.25, but you are probably running 1.0.
The self-contained binaries can be found at
http://calibre-ebook.com/download_linux and are pretty much guaranteed to solve the problem.
Kovid does not support the distro packages: "Please do not use your distribution provided calibre package, as those are often buggy/outdated. Instead use the Binary install described below. "