CSplitterWnd类切分问题！ASSERT_VALID(this)报错

Question

//声明
m_wndSplitter//OnCreate中创建切分类
    CRect rect;
GetClientRect(&rect);
CCreateContext *pContext = (CCreateContext*) lpCreateStruct->lpCreateParams;
m_wndSplitter.CreateStatic(this, 1,2); 
m_wndSplitter.CreateView(0,0, 
RUNTIME_CLASS(CLeftView),
CSize(rect.Width()/4,rect.Height()),
pContext);
      m_wndSplitter.CreateView(0,1,RUNTIME_CLASS(CRightView),CSize(1,1),pContext);

  //OnSize处理
 void CTestView::OnSize(UINT nType, int cx, int cy) 
{
m_wndSplitter.MoveWindow(0,0,cx,cy);
m_wndSplitter.SetColumnInfo(0, (cx/4),0);
m_wndSplitter.SetColumnInfo(1, cx-cx/4, 0);
m_wndSplitter.RecalcLayout();
}当用命令将左侧视图隐藏的时候 报错。
m_wndSplitter.SetColumnInfo(0,10,0); //这行语句报错
m_wndSplitter.SetColumnInfo(1,rt.right-rt.left, 0);//按F11调试 
void CSplitterWnd::SetColumnInfo(int col, int cxIdeal, int cxMin)
{
ASSERT_VALID(this); //这行语句报错，
ASSERT(col >= 0 && col < m_nMaxCols);
ASSERT(cxIdeal >= 0);
ASSERT(cxMin >= 0); m_pColInfo[col].nIdealSize = cxIdeal;
m_pColInfo[col].nMinSize = cxMin;
}
请问是什么错误 谢谢！