DirectX, Visual 6.0: unresolved external symbol _IID_IDirectInput8A

I'm getting the link error "unresolved external symbol _IID_IDirectInput8A" .

There's are two .cpp files.  Each starts like this:

#define WIN32_LEAN_AND_MEAN   // get rid of Windows things we don't need

#include <windows.h>          // included in all Windows apps
#include <winuser.h>          // Windows constants
#include <gl/gl.h>            // OpenGL include
#include <gl/glu.h>           // OpenGL utilty library

The InputSystem.h file starts thus:

#define DIRECTINPUT_VERSION       0x0800

#include <dinput.h>
#include <objbase.h>
#define INITGUID
#include <initguid.h>

I'm using Visual C++ 6.0.  The first include directory is the Direct X 9.0 SDK/Include; so it's not getting the old 6.0 dinput.h.  The DirectX 9.0 library doesn't come first, because if I move it to the head of the lists, I get this link error:  fatal error LNK1103: debugging information corrupt; recompile module

There is another thread on this, at https://www.experts-exchange.com/questions/20796313/DirectInput-sample-code-won't-link-in-C-is-missing-IID-IDirectInput8A.html?query=_IID_IDirectInput8A&clearTAFilter=true .  There's a suggestion there of moving the DirectX library to the head of the list.  I'm not sure why that isn't working for me.

Thanks --
Will Briggs
Lynchburg College