Wiring 3 Way Occupancy Sensor - No Ground Wire

I am installing a 3 way occupancy sensor switch in my laundry room. The laundry room has two light switches that control one light fixture. I've purchased a Lutron Maestro switch for single pole or 3-way. When I opened up the wall where I plan to install the occupancy switch, i found only 3 wires coming out from the wall - a black, white and red. My new sensor switch has two blacks, a blue and a green. One of the blacks is the hot (i taped that one). I assume the red and white are travelers? If that is correct, then where is the ground? The wiring diagram states that the device will not work if it's not grounded.

Attached is an image of the wiring diagram for the sensor, and a picture of the wired light switch that I am replacing. My house was built in 1978 if that matters.
Any help from this group is appreciated!

 

Welcome to the forums.

Your house is fairly new. What type of wiring is it ?
Look into the back of the box. Is it conduit, Metal clad like BX.

What model number is that sensor ?

 

I don't believe it's conduit.
The model # is MS -OPS5MH-WH

 

Thanks for the model number. I couldn't see the diagram clearly. It definitely requires a ground... which you may have based on your type of wiring. You could measure for it with a voltmeter between the two travelers and the box.

In addition to needing a ground.... you will also need to change wiring in the other switch box.