DRVF-5NS isn’t working

[meinarson]

Changing my smart switches from Brand-X to Casita and struggling with the wiring. I thought this one would be simple but it isn’t working. Single switch, two wires and a ground. Connected the ground and the neutral, two wires on the existing switch are both black so one to black and one to red….light would not come on. Switched the black and red and the lights come on, but the switch does nothing.
Ideas?
I installed Caseta in my old house and loved them except for all the buttons. Built a new house and installed Levitron and hate them so now that we have the Diva/Claro option was going to change them. I’m having so much trouble installing them, I’m just about ready to send them all back….help!

[randyc]

If the dimmer has 2 black wires/terminals it doesn't matter which order you connect them. If it has a black wire/terminal and a red wire or brass terminal the black must be power in. The red/brass is power out to the light.

[meinarson]

If the dimmer has 2 black wires/terminals it doesn't matter which order you connect them. If it has a black wire/terminal and a red wire or brass terminal the black must be power in. The red/brass is power out to the light.

That is how it's wired, but the light stays on and the switch does nothing.