Error BCE0018: The name 'World' does not denote a valid type ('not found').

Hey Guys, I really don't know what went wrong: I converted some C# scripts to Boo, but now the "World" and "Chunk" script can no longer access each other! They're both in the same folder (Scripts/Level/). All Threads I found about this error are just about access from different languages (e.g Javascript and C#).

Thanks for help!