AFK mode?

Does anyone else have a problem with AFK mode in DarkRP. When ever i type /afk it says “afk mode is disabled” i have tried finding this in the config.lua and can’t? This is a big problem due to the fact that in DarkRP if someone is Away From Keyboard the server does not automatically put them in AFK mode, wich means they can get loads of money and not be demoted from there job!