[xmonad] Why cannot xmonad find a existng module ?

hi, friends I am using archlinux and both xmonad and xmonad-contrib are installed by pacman. %pacman -Q|grep xmonad xmonad 0.9.1-4 xmonad-contrib 0.9.1-2 %%xmonad --recompile Error detected while loading xmonad configuration file: /home/sw2wolf/.xmonad/xmonad.hs xmonad.hs:20:7: Could not find module `XMonad.Layout.LayoutHints': Use -v to see a list of the files searched for. %ghc-pkg list|grep xmonad xmonad-0.9.1 xmonad-contrib-0.9.1 %pacman -Ql xmonad-contrib|grep LayoutHints xmonad-contrib /usr/lib/ghc-6.12.1/site-local/xmonad-contrib-0.9.1/XMonad/Layout/LayoutHints.hi %ghc-pkg field xmonad-contrib exposed-modules | grep LayoutHints XMonad.Layout.LayoutCombinators XMonad.Layout.LayoutHints Sincerely!