How do I turn on the overlay for traffic in maps? It is greyed out, so cannot turn it on. Any suggestions please? Thanks

You need to get directions to somewhere before it works, and you have to have internet.

It might also be necessary to have 3G turned on. I'm not certain about the last. I didn't manage to turn my overlay on until I turned on my 3G connection, but once I turned on the overlay it no longer seemed to make a difference. I could turn the overlay on and off without 3G turned on.