Please help: trying to capture Enter Key in ComboBox within ToolBar

I have an SDI application with a toolbar (rebar) that contains a
combobox. I need to capture key events (particularly the enter key)
in that combobox. I have followed the MFCIE example from microsoft.

I have also read that in order to capture keypress events in the
combobox, you must dynamically subclass the edit control inside of the
combobox using the OnCtlColor event handler. I have done so like
this:

HBRUSH MyCombo::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor )
{
  if (nCtlColor == CTLCOLOR_EDIT)
    {
         //Edit control
         if (m_xEdit.GetSafeHwnd() == NULL)
            m_xEdit.SubclassWindow(pWnd->GetSafeHwnd());
    }

  HBRUSH hbr = CComboBoxEx::OnCtlColor(pDC, pWnd, nCtlColor);
  return hbr;
}

The call to SubclassWindow returns "1" which is supposed to be a
success. m_xEdit is my derived Edit Control (CComboEdit) which has
handlers for the key events:
BEGIN_MESSAGE_MAP(CComboEdit, CEdit)
    //{{AFX_MSG_MAP(CComboEdit)
    ON_WM_CHAR()
    ON_WM_KEYDOWN()
    //}}AFX_MSG_MAP
END_MESSAGE_MAP()

void CComboEdit::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
   TRACE("KEYDOWN");
}

void CComboEdit::OnChar(UINT nChar, UINT nRepCnt, UINT nFlags)
{
  TRACE("ONCHAR");
}

None of these keypress event handlers is ever hit. Am I missing
something with the dynamic subclassing? I have never done that
before, but it seemed pretty straightforward.

Please help, I've been stuck on this a while.

Thanks,
Jeff