IIS - Restricting specific roles access to folders

i am sure this is very common thing to do. how do i do it. currently i used the ASP.NET Configuration tool but even when not logged in i can access the folders. this is what my Admin/web.config looks like after editing it after searching for info on this, but its not working.

<?xml version="1.0" encoding="utf-8"?>
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
  <location path="~/Admin">
	  <system.web>
		<authorization>
		  <allow roles="admin" />
		  <deny users="*" />
		</authorization>
	  <authentication mode="Forms">
		<forms loginUrl="~/Home/Login.aspx"
		  defaultUrl="~/Default.aspx" />
	  </authentication>
	</system.web>
  </location>
</configuration>