Right. Present doesn't necessarily mean enabled, and you need to look in the BIOS settings for that. Make sure it is enabled.
So, as far as going to sleep, will it sleep if you manually choose sleep from the Start/Shut down menu? Is it only that it won't do it automatically on it's own? FYI, as I said before, "idling" is not sleep.
Idle, in a nutshell, means no active user programs open, no user directed processes running and generally, sitting undisturbed on the desktop for about five to ten minutes. Obviously things that might run automatically like Windows update, other program updaters or processes that load automatically when Windows starts can have an affect on this but generally speaking that is how we describe "idle".
Sleep, obviously, is not that. Sleep is the computer SEEMINGLY powered off, but in reality is only in a very low power state, ready to resume when a defined trigger is activated like touching the keyboard or moving the mouse, depending on what you have settings at in device manager.
See if you can put it to sleep manually, if so, that tells us something.