winxp vc++6 MFC listctrl 双击不响应

.h
afx_msg void OnDblClk(NMHDR* pNMHDR, LRESULT* pResult);

.cpp
ON_NOTIFY(NM_DBLCLK, IDC_LIB_TEXT_LIST, OnDblClk)

void CTextLibDlg::OnDblClk(NMHDR* pNMHDR, LRESULT* pResult)
{
m_nTreeListIndex=-1;
CWnd cwnd;
cwnd.GetDlgItem(IDD_PRO_LABEL_PAGE);
m_hWnd=NULL;
m_hWnd=cwnd.GetSafeHwnd();
if (m_hWnd!=NULL)//判断标签窗口是否打开 多个相同ID对话框打开无效，需要父句柄
{

NMITEMACTIVATE* p = ( NMITEMACTIVATE* )pNMHDR;
UINT nState = m_TextList.GetItemState ( p->iItem, STATE_TREE_MASK );
if (( nState & STATE_ROOT_COLLAPSE ) == STATE_ROOT_COLLAPSE||
(nState & STATE_ROOT_EXPAND ) == STATE_ROOT_EXPAND)
{
m_nTreeListIndex++;
for (int i=0;i<nState;i++)
{
if ( ( nState & STATE_ROOT_COLLAPSE ) == STATE_ROOT_COLLAPSE||
(nState & STATE_ROOT_EXPAND ) == STATE_ROOT_EXPAND)
m_nTreeListIndex++;
}

    }

//  CTextLibDlg::OnDestroy();
}   

}