Apple uses one or more databases (I don't know how many) to map your ISP internet connection to a location in the world.
If you use the network utility to traceroute to that time server, you will see all the routers between you and that apple server. This software does the same thing and reports the hops - if Apple knows where any of the routers close to your mac are located, it will update the location. What it's telling you is it can't pin down where you are based on this information only.
If you can try connecting to a different network or a public network it might be more likely to know where you are. Many business internet connections pool the public internet access and the database is told to ignore that since the traffic isn't coming to apple close to your physical location.
Are you on a home network? Can you call your ISP to see if they allow or prevent location of their customers? It's a problem with the people supplying you with internet and not anything on your computer, so you can't do anything directly to correct it other than change your ISP or figure out how to get it mapped.