How to dynamically add a control to a toolbar?

Hi, please see code blew:

BOOL CMyDialog::OnInitDialog()
{
        ...
     CXTPToolBar *pToolBar = GetToolBar(PA_IDR_TB_GS);
     if ( pToolBar )     
     {          
          CXTPControls *pControls = pToolBar->GetControls();                    
          CString strLevel;

          for ( int nLevel = nLevelNum - 1; nLevel >= 0; --nLevel )
          {
               strLevel.Format( _T("%d"), nLevel );                              
               pControls->Add( xtpControlButton, PA_IDC_PAGE_BTN0 + nLevel, strLevel, 1 );
          }          
     }

        ...
}

But it doesn't work.
Can anybody tell me why and how?
Thanks

Hi,

i use this. and call CreateButtons() after add buttons.

void CXTPDynamicToolbar::UpdateCalc()
{
    CRect rcClient;
    GetParent()->GetClientRect(rcClient);

    CSize sz = CalcDockingLayout(rcClient.Width(), /*LM_HIDEWRAP|*/ LM_HORZDOCK | LM_HORZ | LM_COMMIT);
    MoveWindow(rcClient.left, rcClient.top, rcClient.Width(), sz.cy);
    Invalidate(FALSE);
}


void CXTPDynamicToolbar::CreateButtons()
{
    UpdateCalc();
    m_pControls->CreateOriginalControls();
}

   Jimmy