Help with DLL

I am trying to make a dll in Microsoft VC++ 6 2005

It is a C program

but im getting this error. I dont really understand precompiled headers so i dont know what to do.

Code:

c:\startupplot\startupplot.c(4) : fatal error C1853: 'Debug/StartUpPlot.pch' 
is not a precompiled header file created with this compiler

these are my includes

Code:

#include "stdafx.h"
#include "AlazarApi.h"
#include "AlazarCmd.h"
#include "windows.h"
#include "stdio.h"
#include "conio.h"

My project is set to

Any thoughts?
Thanks.

 

oh yeah and i added those includes to:
startupplot.c
stdafx.h
stdafx.c

 

hmm i just did create a new project and it didnt work

Here are my project>settings

 

i have a C program so i need to include cstdio.h not stdio.h right?

 

also do i need to put all those includes into the stdafx.h file? or do i have to leave it alone?

 

Dump the stdafx file(s). Turn off precompiled headers. The C header for stdio is stdio.h. The C++ header for stdio is cstdio (no .h).

 

dont stdafx and precompiled header make everything run faster?

i have it working now. should i scrap it?