Why can't I see someone's location after they shared it with me on my iPhone?

Why isnt location sharing working on my iPhone?

Is there any way I can use an iPhone with Location Services on without using 3g data?

I dont have the same problem on my phone but it was working just a couple of days ago. Is it possible that my iPhone is just updating its location from somewhere else? Is it possible to find out what program or webpage could be doing this? Thanks in advance. For anyone who has the same problem. The problem was resolved by checking my settings for Bluetooth. I had turned off "Allow background location updates" and also the app that sends me updates in the background. Turning those on fixed the problem.