MapViewOfFile Failing with error code #5, any help?

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C++

Windows

Win7

VisualC++

Hi,
I am receiving buffer from some module. example i received buffer which is produced by below peace of code

CString strTemp = "";
for(int i =0; i < 10000; ++i)
{
  strTemp.Format("Test1-Test2-Test3-Test4-Test5-Test6-Test7===%d;",i);
  m_strMemData = m_strMemData + strTemp;
}

Then i am trying to insert the buffer into file using memory mapped files.
Steps i am doing as part of below peace of code is:
Module#1
1) Creating a file in temp folder
2) Creating memory map file, using CreateFileMapping
these first two parts will be done as part of seperate module.

Module#2:
3) Opening mapped file, using OpenFileMapping
4) Finding granularity using GetSystemInfo
5) In loop mapping the file which is in temp folder, and trying to write by chunk by chunk, using MapViewOfFile and copymemory.
in First iteration mapviewoffile is success, second time if i change the dwFileOffsetHigh, and dwFileOffsetLow then the MapViewOfFile function is failing with error code#5.
please help if any one have solution.
some one suggested SetFilePointer, i tried that also, but not worked. whether i need to try this setfilepointer with mapped file pointer / opened file pointer or which one. ?
Please find code :

LPVOID  pViewMMFFile;
DWORD   granularity, dwSizeContent;
DWORD64 dwOffSetStart;
HANDLE  hFile, hFileMMF, hFileMMFTemp;
char    szName[256] = "PROCESS1";
char    szTmpFile[256];
char    szMMFile[256];
SYSTEM_INFO sysInfo;

////////////////////////////////////////
/* Create temporary file for mapping. */
////////////////////////////////////////
GetTempPath (256, szTmpFile);

strcat( szTmpFile, "temptestbuf.txt");
strcpy( szMMFile, szTmpFile);

SECURITY_ATTRIBUTES sa;
sa.bInheritHandle = TRUE;
sa.lpSecurityDescriptor = NULL;
sa.nLength = sizeof(sa);

////////////////////////////////////////////
/* If file created, continue to map file. */
////////////////////////////////////////////
hFile = CreateFile (szMMFile,
	GENERIC_WRITE | GENERIC_READ,
	FILE_SHARE_READ|FILE_SHARE_WRITE,
	&sa,
	OPEN_ALWAYS,//CREATE_ALWAYS,
	FILE_ATTRIBUTE_READONLY | FILE_FLAG_SEQUENTIAL_SCAN,
	NULL);
CString str;
str = szMMFile;
if( hFile == NULL )
{
	DWORD dwErr1 = GetLastError();
	ASSERT(FALSE);
	return;
}

/*----------------------------
CREATING FILE DONE.
----------------------------*/

hFileMMFTemp = CreateFileMapping(hFile, &sa, PAGE_READWRITE, 0, 0, szName);

if(hFileMMFTemp == NULL)
{
	DWORD dwErr2 = GetLastError();
	ASSERT(FALSE);
	return;
}
CloseHandle(hFile);
/*--------------------------------------------------------
	----------- First module completed -----------.....
--------------------------------------------------------*/

dwSizeContent = m_strMemData.GetLength(); //GetFileSize(hFile, NULL);
dwOffSetStart = 0;
/*----------------------------
CREATING FILE MAPPING IS DONE.
----------------------------*/
//Open named file mapping object.
hFileMMF = OpenFileMapping(FILE_MAP_ALL_ACCESS,FALSE,szName);

if(hFileMMF == NULL)
{
	DWORD dwErr3 = GetLastError();
	ASSERT(FALSE);
	return;
}
GetSystemInfo(&sysInfo);
granularity = sysInfo.dwAllocationGranularity;
//SetFilePointer( hFileMMF, granularity, NULL, FILE_BEGIN);
do
{
	pViewMMFFile = (unsigned short*)MapViewOfFile(hFileMMF, FILE_MAP_ALL_ACCESS, (DWORD)dwOffSetStart >> 32,
		(DWORD)dwOffSetStart & 0xFFFFFFFF, granularity);
	
	if(pViewMMFFile == NULL)
	{
		DWORD dwErr4 = GetLastError();
		ASSERT(FALSE);
		return;
	}
	
	if (dwOffSetStart+granularity < dwSizeContent)
		dwOffSetStart+=granularity;
	else
		dwOffSetStart = dwSizeContent;

	//CopyMemory((LPVOID)pViewMMFFile, pTempBinary, dwLength );
	UnmapViewOfFile(pViewMMFFile);
	

//Is this the right way to ....??
	//SetFilePointer( pViewMMFFile, granularity, NULL, FILE_BEGIN);
}
while( dwOffSetStart < dwSizeContent );

SetEndOfFile(pViewMMFFile);
CloseHandle(hFileMMF);

CloseHandle(hFileMMFTemp);	

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