How to enable Scrollbar in Ribbon Bar

I added a gallery which includes dozens of  picture items  into a Ribbon group ,but the scrollbar on the gallery was unable to use. How to enable it, please help me out.

the left one gallery is what I added. The right two are in the samples.

BOOL CMainFrame::CreateRibbonBar()
{

     --- ---

    CXTPRibbonTab* pTabGallery = pRibbonBar->AddTab(ID_TAB_GALLERIES);

 

//m_pItemsPictures is defined as CXTPControlGalleryItems* m_pItemsPictures  in MainFrame.h;

m_pItemsPictures=CXTPControlGalleryItems::CreateItems(GetCommandBars(),10000);
  m_pItemsPictures->SetItemSize(CSize(60,50));
  for (int nCount=0;nCount<10;++nCount)
  {
   m_pItemsPictures->AddItem(new CGalleryItemThumbnail());
  }

 

CXTPRibbonGroup* pGroup = pTabGallery->AddGroup(ID_GROUP_INLINE);
  pGroup->SetControlsCentering(TRUE);
  

  
  CXTPControlGallery* pPictureGallery=new CXTPControlGallery();
  pPictureGallery->SetControlSize(CSize(200, 60));
  pPictureGallery->SetResizable();
  pPictureGallery->SetItemsMargin(0, 1, 0, 1);
  pPictureGallery->ShowLabels(FALSE);
  pPictureGallery->ShowScrollBar(TRUE);
  pPictureGallery->ShowBorders(TRUE);
  pPictureGallery->SetItems(m_pItemsPictures);
  pGroup->Add(pPictureGallery,10000);
  ---

 

Guess problem that this control is disabled. Add some update handler for control and enable it.