#include "executor/spi.h" throwing errors

Hi,
I'm trying to use SPI for database connectivity at the server side.

My database is intialized at /usr/local/pgsql/hps

spi.h is at the follwoing location

/usr/include/pgsql/server/executor.

I have a C file that has the SPI code and is located at /usr/local/pgsql/hps
I thin file i do #include "executor/spi.h"

This throws hell lot of errors (hundreds of them), even if i don't have any SPI code in my C file as of now.

Can anyone please tell me whats going wrong and what header files should be kept where?

Thanks in advance,

~Harpreet