MFC 线程中发送最小化消息失败

 DWORD WINAPI RecThread(LPVOID lparam)
{
CTestMesDlg *pDlg = new CTestMesDlg;
pDlg->Receive();
return 0;
}
void CTestMesDlg::Receive()
{ 
::SendMessage(m_hWnd,MY_SC_MINISZIE,SC_MINIMIZE,0);
return ;
}
LRESULT CTestMesDlg::DefWindowProc(UINT message,WPARAM wParam,LPARAM lparam)
{
LRESULT lrst = CDialog::DefWindowProc(message,wParam,lparam);
if (!::IsWindow(m_hWnd))
return lrst;
if (message == MY_SC_MINISZIE && wParam == SC_MINIMIZE)
{AfxMessageBox("你好！");}
return lrst;}
void CTestMesDlg::OnBnClickedButton2()
{// TODO: 在此添加控件通知处理程序代码 
 HANDLE hThread = CreateThread(NULL,0,RecThread,NULL,0,NULL); 
 return ;
}