Includes not resolving

I'm unable to get Eclipse 10.1 to include anything not in the current directory or the built-in directories.

For example, I have:# include "net.h"# include "./subdir/net.h"# include "c:/FullPathTo/subdir/net.h"# include "subdir/net.h"

I always get "No such file or directory", even though I can open the file

from the project space, Explorer, or my external editor.

I try to add include paths in the Project->Properties->C/C++General->Includes, but the builder never inserts a "-I mypath" for anything I enter, either as a workspace or filesystem path.

Windows 7 x64, Intel Core i7.