how to use StgOpenStorageEx

Hi all,

when i use StgOpenStorageEx(L"C:\\myfile.xml", .... ), it work well
but i use StgOpenStorageEx( lpszWFile, ), not work (see code below)

any idea? i convert CString to WCHAR incorrect?

void changeInfo(CString sFileName)
{
 IPropertySetStorage *pPropSetStg = NULL;
 IPropertyStorage *pPropStg = NULL;
 PROPSPEC propspec;
 PROPVARIANT propWrite;
 PROPVARIANT propRead;
 HRESULT hr = S_OK;

 WCHAR* lpszWFile = new WCHAR[MAX_PATH];

 CFile cFile;
 if ( cFile.Open(sFileName, CFile::modeRead) )
 {
  sFileName = cFile.GetFilePath();
  cFile.Close();
 }
 else
  return;

 LPTSTR lpStr = sFileName.GetBuffer( sFileName.GetLength() );
 int nLen = MultiByteToWideChar(CP_ACP, 0,lpStr, -1, NULL, NULL);
 MultiByteToWideChar(CP_ACP, 0, lpStr, -1, lpszWFile, nLen);

 // Open a file and a property set within it.
 hr = StgOpenStorageEx( lpszWFile,//L"C:\\myfile.xml",
     STGM_DIRECT|STGM_SHARE_EXCLUSIVE|STGM_READWRITE,
     STGFMT_ANY,
     // STGFMT_STORAGE //Structured Storage property sets
     // STGFMT_FILE //NTFS file system property sets
     0,
     NULL,
     NULL,
     IID_IPropertySetStorage,
     reinterpret_cast<void**>(&pPropSetStg) );

 sFileName.ReleaseBuffer();
 delete[] lpszWFile;

 DWORD Result = 0;
 if( FAILED(hr) )
 {
  Result = GetLastError();
  //throw L"Failed StgOpenStorageEx";
  return;
 }