Yesod devel fails, thought cabal build succeeds

I am relatively new to Haskell, coming from F# (a Microsoft language).

I have created a Ye开发者_如何学Pythonsod project from the scaffolder, played with it a bit, tweaked stuff, but then it stopped working, with this error message (after all modules were built successfully):

devel.hs: D:\yesod\projects\test101\dist\build\HStest101-0.0.0.o: unknown symbol `___stginit_test101zm0zi0zi0_HandlerziPage_'
devel.hs: devel.hs: unable to load package `test101-0.0.0'
Exit code: ExitFailure 1

By using cabal directly (cabal build, cabal install, dist\build\test101\test101) I was able to run the application, but this is really annoying.

What can I do?

Thanks!

---

I think you need to add your new modules (Handler.Page in particular) to the cabal file.