CPaneDialog inside CDockablePane question

I try to put 2 CPaneDialog inside CDockablePane (just like CFormView), but somehow, I don't see the splitter between 2 dialog panes.  Is anyone has any idea why?

Here is sample code, that create 2 dialog panes

 DWORD dwNoCloseBarStyle = AFX_DEFAULT_DOCKING_PANE_STYLE & ~AFX_CBRS_CLOSE;

 if ( !m_AlertMarginalView.Create( _T( "Marginal" ), this, FALSE,
  MAKEINTRESOURCE( IDD_DLG_BAR ),
  WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN | CBRS_TOP,
  ID_VIEW_DLGBAR, dwNoCloseBarStyle ) )
 {
  TRACE0( "Failed to create Dialog Bar\n" );
  return FALSE;      // fail to create
 }

 if ( !m_AlertCriticalView.Create( _T( "Critical" ), this, FALSE,
  MAKEINTRESOURCE( IDD_ALERT ),
  WS_CHILD | WS_VISIBLE | WS_CLIPSIBLINGS | WS_CLIPCHILDREN | CBRS_BOTTOM,
  ID_VIEW_DLGBAR + 1, dwNoCloseBarStyle ) )
 {
  TRACE0( "Failed to create Alert Bar\n" );
  return FALSE;      // fail to create
 }

 m_AlertCriticalView.DockToWindow( this, CBRS_TOP );
 m_AlertMarginalView.DockToWindow( this, CBRS_BOTTOM );

Thanks,

Steve