Using A Leviton Dimmer With Another non smart switch

[JDRoberts]

When you replace one switch in a three-way set up with a networked switch, you will also have to rewire any other switches on the circuit. You cannot leave the former dumb switch in place as the wiring pattern is typically different. This information should be in the user manual for the device that you bought already.

See the following for more details. Although it is discussing GE switches, the Leviton switches use similar wiring:

[FAQ] GE 3-Way Wiring

I’ve decided to put this FAQ together to help those with questions about installing GE 3-way switches. Definitions of terms: Line: The hot wire from the breaker (usually black) Neutral: The return wire for circuits (usually white) Load: The wire that will be hot when the circuit is completed to your light (usually black) Traveler: In existing 3-way wiring, this wire toggles hot between two switches. In a smart switch 3-way configuration, a smaller charge is looped through the add-on switch. Some things to know: 3-way wiring for smart switches is different than standard 3 way wiring. You cannot use dumb 3-way switches with most smart switches (You must purchase the matching GE add-on switch to wire with your GE smart master switch). If the line is wired into the light fixture, you …