Short answer: You need visible set to 0 and enabled set to 1.
Long Explanation: This is because it is not always visible but should always be enabled in case a class switches to a weapon without a clip, if that makes sense. In other words: enabled is, in short, if the element has the capacity to be visible, and visible is if it actually is or not.
Here's every combination of settings dissected: both set to 1 is for things that are always visible, like if you have a hud crosshair. Visible 0 and enabled 1 is what I just explained: things that are sometimes visible. Both set to 0 is disabled (sometimes this doesn't work though: if you're disabling something and setting both to 0 doesn't remove it try setting fgcolor to 0 0 0 0 or setting x or y pos to 9999). Enabled 0 Visible 1 would still be invisible because enabled overrides visible. Hope that helped!
EDIT: omni ninjad me but hopefully the explanation helps somebody.