About CXTSplitterWnd, how to switch?

BOOL CMainFrame::OnCreateClient(LPCREATESTRUCT lpcs, CCreateContext* pContext)
{
 // TODO: Add your specialized code here and/or call the base class
 if (!m_wndSplitter.CreateStatic(this, 1, 2))
 {
  TRACE0("Failed to create splitter window\n");
  return FALSE;
 }
 m_wndSplitter2.CreateStatic(&m_wndSplitter,3,1,WS_CHILD|WS_VISIBLE, m_wndSplitter.IdFromRowCol(0, 1));
// m_wndSplitter3.CreateStatic(&m_wndSplitter,3,1,WS_CHILD|WS_VISIBLE, m_wndSplitter.IdFromRowCol(0, 2));

 if (!m_wndSplitter.CreateView(0,0, RUNTIME_CLASS(CView1),
  CSize(100, 100), pContext))
 {
  TRACE0("Failed to create CView1\n");
  return FALSE;
 }

 
 if (!m_wndSplitter2.CreateView(0,0, RUNTIME_CLASS(CGraphView),
  CSize(00, 100), pContext))
 {
  TRACE0("Failed to create CView2\n");
  return FALSE;
 }
 
 if (!m_wndSplitter2.CreateView(1,0, RUNTIME_CLASS(CTrafficView),
  CSize(100, 100), pContext))
 {
  TRACE0("Failed to create CView3\n");
  return FALSE;
 }
 
 if (!m_wndSplitter2.CreateView(2,0, RUNTIME_CLASS(CInfoView),
  CSize(100, 100), pContext))
 {
  TRACE0("Failed to create CView4\n");
  return FALSE;
 }

  CRect r;
 GetClientRect(&r);
 
 m_wndSplitter.SetRowInfo( 0, r.Height()/5, 0 );

 return TRUE;
 return CFrameWnd::OnCreateClient(lpcs, pContext);
}

 

void CMainFrame::OnSwapview()
{

 CView* pView = (CView*)m_wndSplitter2.GetPane(2,0);
 m_wndSplitter2.SwitchView(0, 0, pView);
}

 

1    CView* pView = (CView*)m_wndSplitter2.GetPane(2,0);
2    m_wndSplitter.SwitchView(0, 0, pView);

 

Switch throw out  an Assert，why？