c++ - Visual Studio Intellisense finds function, but compiler doesnt

I am working with OpenSSL to try and get the SHA512 Hash
function to work. When I am writing the code, Visual Studio's intellisense finds the
function SHA512as well as all of the parameters that are
included with it, but when I go to build the project, I get the error, "unresolved
external symbol SHA512 referenced in function main." Here is what I have so far, it's
based on a small example href="http://www.askyb.com/cpp/openssl-sha512-hashing-example-in-cpp/" rel="nofollow
noreferrer">here.

stdafx.h

//
            stdafx.h : include file for standard system include files,
// or project
            specific include files that are used frequently, but
// are changed
            infrequently
//


#pragma
            once

#include "targetver.h"

#include
            
#include 
#define
            _ATL_CSTRING_EXPLICIT_CONSTRUCTORS // some CString constructors will be
            explicit
#define _AFX_NO_MFC_CONTROLS_IN_DIALOGS // remove support for MFC
            controls in dialogs


#ifndef
            VC_EXTRALEAN
#define VC_EXTRALEAN // Exclude rarely-used stuff from Windows
            headers
#endif

#include 
#include
             // MFC core and standard components
#include 
            // MFC extensions
#ifndef _AFX_NO_OLE_SUPPORT
#include
             // MFC support for Internet Explorer 4 Common
            Controls
#endif

#ifndef
            _AFX_NO_AFXCMN_SUPPORT
#include  // MFC support for Windows
            Common Controls
#endif // _AFX_NO_AFXCMN_SUPPORT

#include
            



// TODO: reference
            additional headers your program requires here
#include
            

test.cpp

#include
            "stdafx.h"
#include 
#include
            


int main() {


            unsigned char digest[SHA512_DIGEST_LENGTH];
 char string[] = "hello
            world";

 SHA512((unsigned char*)&string, strlen(string),
            (unsigned char*)&digest);

 char mdString[SHA512_DIGEST_LENGTH *
            2 + 1];

 for (int i = 0; i < SHA512_DIGEST_LENGTH;
            i++)
 sprintf(&mdString[i * 2], "%02x", (unsigned
            int)digest[i]);


 printf("SHA512 digest: %s\n",
            mdString);

 return
            0;
}

I have
even checked and confirmed that SHA512 is in the sha.h file that is included in the
stdafx.h file as well.