new 3-way wall dimmer switch behaves "weirdly"

[dave]

bought and installed a 3 way dimmer on our staircase: upstairs still on its original wall switch, downstairs (at base of stairs) has been changed from switch to the (correct-type '3 way') dimmer. lite fixture halfway up staircase.

I was under the impression that the light should still be able to be turned on from "either end" regardless of what position the other switch is in, correct? that's how it formerly worked, anyway, with the two wall switches. but NOW, the upstairs switch must be in the 'on' position in order for the dimmer to turn on the wall lamp...

wiring all done correctly, near as I can tell, and the only even remotely possible problem is the fact that our house (3 yrs old now) originally had the romex 'bare copper' ground NOT hooked to the green wire on the switch*, where the dimmer now is installed (and the bare copper ground now hooked to the dimmer green wire)

could the ground "now being used" be causing this strange behavior?

also, if the dimmer is turned OFF, upstairs switch will NOT turn lite ON. it's a "full sweep knob type dimmer, with the 'push on/push off' feature at any setting, Lutron, brand new, from a big box store...

*apparently, this 'no ground wire in use' situation is 'correct' for our home's wiring - I've noticed same situation elsewhere in our house, inside other wall switch boxes...

thanks for educating me, clues and other tips :-)

[Travis Jordan]

You shouldn't have any problem replacing a 3-way switch with a 3-way dimmer. The ground connection isn't the issue.

I would guess you've got it wired incorrectly. Maybe this will help:

[jstp]

1. If the upstairs switch needs to be on, you didn't wire it correctly. Re-check.

1. If you dim down the light with the dimmer, the upstairs switch will turn on a "dimmed" light. In the same way, if you dim it down to "no light", the upstairs switch will have no effect. This is normal.

[Steve B.]

Here's the gotcha...

Not all three way switches have the same connections in the same place. In this case I suspect that even though you hooked it up just like the old the new one works different. Try to put your old switch back in place and get it working properly then try again with the 3way paying extra attention to how the connections are labeled instead of where they are located.

Steve B.