cabal "fails" with no explanation

stefan@stefans:/usr/local/src/xmonad$ runhaskell Setup.lhs clean -v5 cleaning... stefan@stefans:/usr/local/src/xmonad$ echo $? 1 stefan@stefans:/usr/local/src/xmonad$ ghc -V The Glorious Glasgow Haskell Compilation System, version 6.7.20070502 stefan@stefans:/usr/local/src/xmonad$ configure, build, and install all also work but return 1. The same issue is observed with X11-extras. Stefan