Missing block Magic

Hi,

I want to make a function in C for postgresql, this is the code:

#define _USE_32BIT_TIME_T
#define BUILDING_DLL 1

#include "postgres.h"
#include "fmgr.h"
#include "executor\spi.h" /* SPI - Server Programming Interface */

#if defined(_MSC_VER) || defined(__MINGW32__)
#define PG_GETINF_EXPORT __declspec (dllexport)
#else
#define PG_GETINF_EXPORT
#endif

PG_MODULE_MAGIC;

PG_GETINF_EXPORT PG_FUNCTION_INFO_V1(suma);

Datum suma(PG_FUNCTION_ARGS)
{
int32 arg = PG_GETARG_INT32(0);
  
PG_RETURN_INT32(arg + 1);
};

This compile sucessfull, but when I try to use:

CREATE OR REPLACE FUNCTION add_one(integer)
RETURNS integer AS
'C:\Documents and Settings\Administrador\Escritorio\test\test.dll', 'pg_finfo_suma'
LANGUAGE 'c' VOLATILE STRICT
COST 1;

I get it:

ERROR:  biblioteca «C:\Documents and Settings\Administrador\Escritorio\test\test.dll» incompatible: no se encuentra el bloque mágico
HINT:  Se requiere que las bibliotecas de extensión usen la macro PG_MODULE_MAGIC.

Please help me! I don't know to do.

Thanks