[Haskell-cafe] unable to run ghci (7.4.1)?

Dear list, I build haskell-platform 2011.04 by gentoo ~amd64 haskell overlay. But I can't run ghci even I rebuilt ghc or run haskell-updater, error message: ghci GHCi, version 7.4.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... ghc: /usr/lib64/ghc-7.4.1/base-4.5.0.0/HSbase-4.5.0.0.o: unknown symbol `stat' ghc: unable to load package `base' Do you have some ideas how to avoid this error? Many thanks. Best Regards Baojun