问题： if(FAILED(hr = mainbuffer->
         {
             MessageBox(hWnd,TEXT("Create ....."),TEXT("Error"),MB_OK);
              return 0;
         }
       总是创建失败，弹出对话框。   代码是照着某网站敲的。
顺便求解QueryInterface(IID_IDirectSound3DBuffer8,(LPVOID*)&sbuffer)是干什么用的？

代码如下：
         //声音测试
         LPDIRECTSOUNDBUFFER8    sbuffer = NULL;
         LPDIRECTSOUND8            device = NULL;
         CWaveFile* file = NULL;
         HRESULT hr;
         
         if(FAILED(hr = DirectSoundCreate8(NULL, &device, NULL)))
         {
             MessageBox(hWnd,TEXT("Create Sound"),TEXT("Error"),MB_OK);
             return 0;
         }
         if(FAILED(hr = device->SetCooperativeLevel(hWnd, DSSCL_PRIORITY)))
         {
             MessageBox(hWnd,TEXT("Create Cooperative"),TEXT("Error"),MB_OK);
             return 0;
         }

         file = new CWaveFile;
         file->Open(_T("D:\\mySAO\\handsonic.wav"), NULL, WAVEFILE_READ);
         DSBUFFERDESC desc;
         ZeroMemory(&desc,sizeof(DSBUFFERDESC));

         desc.dwSize = sizeof(DSBUFFERDESC);
         desc.dwFlags = DSBCAPS_GLOBALFOCUS | DSBCAPS_CTRLFX| DSBCAPS_CTRLPOSITIONNOTIFY |DSBCAPS_GETCURRENTPOSITION2;
         desc.dwBufferBytes = file->GetSize();
         desc.lpwfxFormat = file->m_pwfx;

         LPDIRECTSOUNDBUFFER mainbuffer = NULL;
         if(FAILED(hr = device->CreateSoundBuffer(&desc,&mainbuffer,NULL)))
         {
             MessageBox(hWnd,TEXT("Create soubdbuffer"),TEXT("Error"),MB_OK);
             return 0;
         }
         if(FAILED(hr = mainbuffer->QueryInterface(IID_IDirectSound3DBuffer8,(LPVOID*)&sbuffer)))
         {
             MessageBox(hWnd,TEXT("Create ....."),TEXT("Error"),MB_OK);
              return 0;
         }
         mainbuffer->Release();

         LPVOID lock;
         DWORD  len;
         DWORD  write;
         sbuffer->Lock(0, 0, &lock, &len, NULL, NULL, DSBLOCK_ENTIREBUFFER);
         file->Read((BYTE*)lock, len, &write);
         sbuffer->Unlock((LPVOID)lock, len, NULL, 0);
         sbuffer->SetCurrentPosition(0);