It sounds like you're trying to access the files in the directory Calibre keeps the library in directly. Although it's been said in the comments to the ticket you filed, I'm gonna suggest you read
this thread. It tries to explain why Calibre works the way it does and why bad things happen if you try to mix your own way with the way Calibre does things.
(And, as a side note, yes, we've had that argument countless times already, ain't gonna change. Get used to it.)