Hi,
Thought I would chime in...
I am having the same issue. I am running 10.7.4 and I have two other Macs, 10.5.8, and 10.6.8 If I screen share out to the other, older Macs, they both show the screen share binocular icon. If I share from either older Mac to the 10.7.4 Mac, I cannot see that anyone is screen sharing with me. I too tried to select the box you are referring to in sys prefs.sharing.remote management and am unable to do so.
I have a hunch this issue may have been during updates as I seem to recall the icon always showing up but would not now swear to it.
As a result, I have spent hours trying to find a simple way to simply see if any computers are connected to me, or "disconnect all" or ??? I do not like the feeling that someone could be viewing my screen unbeknownst to me, and don't feel like fooling with terminal or, for that matter, anything more involved than seeing an icon in my menu bar!
KC