removable access gpo not working

Hi, I am trying to disable read access to usb pens on Windows 8 through a user based GPO. I have created a GPO that Group Policy Modeling and Group Policy Results wizards from the Group Policy Management program shows is getting applied but for some reason I can still access the usb pen. I have followed this

http://social.technet.microsoft.com/Forums/windows/en-US/5eb6ac82-49a2-4a62-9b19-28ed62546f58/removable-storage-access

and the suggestions have not helped.

If in the same policy I disable CD read access for example the CD drive won't work just as expected but if I disable access on the removable storage I can still access the USB stick.

Any ideas where I can check?

Thanks