Problems with GetQueuedCompletionStatus and ReadDirectoryChangesW at time of notification

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C++

MFC

Hello I have a problem

I'm watching for a files by

ReadDirectoryChangesW

that's my thread where I'm waiting for packets:

CFileMonitoringManager *pThisClass = (CFileMonitoringManager*)lpParam;

	TCHAR szFileNameBuffer[MAX_PATH];
	DWORD dwBytes = 0;
	DWORD cbOffset = 0;
	CSubscribeTarget *pObject = NULL;
	LPOVERLAPPED lpOverlapped = NULL;    
	FILE_NOTIFY_INFORMATION *pNotifyInfo = NULL;

	BOOL bTwoTimes = FALSE;

	while(pThisClass->m_hCompPort)
	{
          if (::GetQueuedCompletionStatus(pThisClass->m_hCompPort, &dwBytes, 
(LPDWORD)&pObject, &lpOverlapped,  INFINITE))
		{
	          pNotifyInfo = (PFILE_NOTIFY_INFORMATION)pObject->m_NotifyBuffer;
		  DWORD dwBytesRead = 0;

		  do
		  {
                       memset(szFileNameBuffer, 0, sizeof(TCHAR) * MAX_PATH);
                       TCHAR* szFileName = 
GetTCHAR(pNotifyInfo->FileName, pNotifyInfo->FileNameLength, szFileNameBuffer, MAX_PATH);
		
                       //My special code
		       cbOffset = pNotifyInfo->NextEntryOffset;
		pNotifyInfo = (PFILE_NOTIFY_INFORMATION)((LPBYTE)pNotifyInfo + cbOffset);
		  } 
		   while(cbOffset);

		lpOverlapped->Offset += dwBytes;

		if(!pObject->ReadingDirectory())
			return 0;
		}
		pNotifyInfo = NULL;
		dwBytes = 0;
		lpOverlapped = NULL;
		pObject = NULL;

For example I watching for directory and file D:\TESTS\Input.txt.
When I'm changing some another file like D:\TESTS\Input1.txt, I get notification

pNotifyInfo->FileName

is good name Input1.txt and length 20, I skip my special code. But next time when I change D:\TESTS\Input.txt I get in

pNotifyInfo->FileName

Input.txtt and Length 18. Why?
I tried NULLed all params but it didn't help.

Please help me I can't understand why I get wrong name like buffer wasn't clean.
Thank you!