Usage of VsCommands2K.EXPAND_CHILDREN

I am expecting a call back at QueryStatusOnNode & ExecCommandOnNode when any item is expanded in the Solution Explorer 

Following is the code I have in my FolderNode, When I expand a folder from the solution explorer, I expect one of these Expand command be queried for..but i am not getting the call back

protected override int QueryStatusOnNode(Guid cmdGroup, uint cmd, IntPtr pCmdText, ref QueryStatusResult result)
{
  if(cmdGroup == VsMenus.guidStandardCommandSet97)
  {
      case VsCommands.Expand:
      case VsCommands.ExpandAll:
      case VsCommands.ExpandImages:
      case VsCommands.ExpandLinks:
      case VsCommands.ExpandPages:
	result |= QueryStatusResult.SUPPORTED | QueryStatusResult.ENABLED;
	return VSConstants.S_OK;
   }
   else if(cmdGroup == VsMenus.guidStandardCommandSet2K)      
   {
      if ((VsCommands2K)cmd == VsCommands2K.EXPANDSELECTION || (VsCommands2K)cmd == VsCommands2K.EXPANDCONTROLS || (VsCommands2K)cmd == VsCommands2K.EXPAND_CHILDREN )
      {
        result |= QueryStatusResult.SUPPORTED | QueryStatusResult.ENABLED;
        return VSConstants.S_OK;
      }
   }
}

Any help on this would be appreciated

Thanks in advance