[xmonad] Creating a new package with cabal-install

I am just trying to follow this tutorial: http://www.haskell.org/haskellwiki/Xmonad/xmonad_development_tutorial As I would like to use cabal-install, I tried "cabal install" from the XMonadContrib directory to build and install the HelloWorld module, but I got an error message in section 2.3 of the tutorial: Resolving dependencies... Configuring xmonad-contrib-0.9.1... Preprocessing library xmonad-contrib-0.9.1... cabal: can't find source for Xmonad.Actions.HelloWorld in ., dist/build/autogen cabal: Error: some packages failed to install: xmonad-contrib-0.9.1 failed during the building phase. The exception was: exit: ExitFailure 1 What's wrong? Cheers, Ralph