Maybe it will save you the 2.5hrs I spent searching for the answer - After a lot of research, youtubing, and searching this community I finally made the call to Tech Support - here's what I found.

I have a BLACK, WHITE and a GROUND wire coming out of my box - nothing else. When the original lightswitch was in there I did notice that the ground was connected to the box itself, and the BLACK and WHITE wires were connected to the normal switch terminals. Nothing was connected to the ground terminal on the switch.

Tried every stinkin' combination of wires on the MS-OPS2, and nothing worked - the closest I came was the light came on, but none of the functions of the sensor were working at all, and I could not shut off the light, it was stuck to ON.
That wiring combination was - One of the BLACK to BLACK, One of the BLACK to WHITE, and the other two, bare and white to GROUND.

Tech Support informed that this behavior is because there is not a clear path to ground so the MS-OPS2 isn't getting sufficient ground reference. This is required for this sensor to work properly. My house is fairly old, 1976. I guess back then they really didn't a **** about ground. :)

However, there is a solution - if you purchase the DIMMER version of the MS-OPS2 - which is MSCL-OP153M - this version does not require a clear path to ground. So I went back to Amazon, returned my MS-OPS2, and purchased the dimmer version. We'll see how that works. If it does NOT work, I will post back here and say so.

Good Luck!

PS- LUTRON - it may help to mention this on the product page for the MS-OPS2, you may get less hassle.