How to restrict access to a Public Folder in Dashboard Module

Hi 

I have a folder in the 'public' directory in the Dashboard Module, i only want certain User Groups to be able to veiw the contents of the folder how could i go about this? I have tried to stop a user group expanding the folder, on right clicking the folder and selecting expand this works, however on clicking the small arrow next to the folder the folder expands and the contents can be veiwed. Below is the current code I have tried. Any help would be greatly appreciated

Function ActionCanExecute(ActionName)

IF AnalysisItemFolder_Fields("AIF_NAME").Value = "Defect Management" then

     IF ActionName = "Analysis.ExpandAll" and User.IsInGroup("TDAdmin") THEN
         ActionCanExecute = False
        msgbox "You do not have permission to perform this action"
     ELSE
         ActionCanExecute = True
      End If
End If