Outer Limits 4x4 Board

Hey all;
Might be a dumb question, but I have just wired in some accessory gauges into my cruiser Ute and I have taken the power wire for the gauge bulbs buy simply tapping into an exiting gauge bulb power wire.
However here is my problem, the Ute has a dimmer switch and now my accessory gauge works back to front from the other gauges, eg when the dash brightens my new gauges dim.
I’m guessing that the existing bulbs may be positive earth?????
If I take the dimmer switch out of the circuit then all bulbs old and new work fine, so I am a bit confused.
Any help muchly appreciated.
Thanks
Pony

Told you it was a dumb question.
I had another look this arvo and found out that I need to return the negative to the same system as the positive came from.
So it is all good now.
Pony