Dimmer switch doesn't work properly after replacing a light fixture

If the fixture (new one) is fluorescent and the one you took out was incandescent then that may be the problem.

Nope, both are incandescent. :-/

I would be interested to see what the make and model of your "new" fixture is for a couple of reasons.

1: There are certain brands that make fixtures specifically for dimmability and some specifically not for such a function.

2: If the brand of the dimmer and the brand of the fixture do not match, it is possible that the technology to power both are not compatible with each other.

3: The similar situation can (and usually does) occur when using dimmers, fixtures and light bulbs that do not connect with each other.

In a perfect electrical world, everything would be universal and thus, everything would be compatible with everything to avoid issues such as these.
However, since this is NOT a perfect world, and a perfect electrical world can not exist within this one...you need to try your best to make sure that everything matches. If not by brand, then DEFINITELY my the *functions* that each part of this equations has; I.E. dimmability and light bulb compatibility!!

I hope this helped a little bit, let me know if you have any other questions!

~THDGIRL

Thanks for the info however in this case I'm sure he just got the wiring goofed up. People shouldn't be monkeying around with electrical if they don't really understand what they're doing.

BV000193 that is so helpful. you should really figure out something else to do with your life other than looking for opportunity to be an obnoxious jack as

Wow that about says it...