Close MDI Child Window Fail ???

[_skidrow_vn_]

in my MDI app.......I inserted a CRecordView-base Class named CLogin when I input my ID and my Password .... I want this form disappear but when app run to this line GetDocument()->OnCloseDocument(); Login Form is hide and a Error MessageBox show Unhandled exception in QLBH.exe (MFCD42D.DLL): 0xC0000005: Access Violation. and cursor point to this line in DBCORE.CPP like following:

BOOL CRecordset::IsOpen() const
	// Note: assumes base class CRecordset::Close called
{
	if (m_hstmt == NULL)     // Error in this line //
		return FALSE;
.....
}

I tried use: SendMessage(WM_CLOSE) or SC_CLOSE or GetParentFrame()->SendMessage(WM_CLOSE); but no result help me thank

void CLogin::OnOk() 
{
	// TODO: Add your control notification handler code here
	CString	strID,strPass;

	m_editID.GetWindowText(strID);
	m_editPass.GetWindowText(strPass);

	m_pSet->MoveFirst ();
	while(!m_pSet->IsEOF())
	{
		if(!strID.Compare(m_pSet->m_ID))
		{
			if (!strPass.Compare(m_pSet->m_Pass))
				AfxMessageBox("ok");
			else
				AfxMessageBox("wrong");

			GetDocument()->OnCloseDocument(); //Error//:eek:
			//GetParentFrame()->SendMessage(WM_CLOSE); // error //:eek:
		}
		
		m_pSet->MoveNext();
	}
	
}