There are three completely different components that I've found running the circuit in
off the shelf light dimmers (the main circuitry can be run by different primary devices,
not all dimmers are constructed using the same components).
My first thought was that you might have a dimmer that was not designed to work with
the motor in the ceiling fan, that might still be the problem.
Some fans have all kinds of internal circuitry for speed control (and also external
slide switches on the outside of the fan itself to limit speed-make sure you don't
have one of those screwing you up).
What I'm saying is that you might have a controller that was designed to operate a
SPECIFIC MANUFACTURER'S line of ceiling fans, and it's not compatible with the one
you have, ...just one other thing to consider here.
This is one of those problems that we wish we could just look at, and maybe see the
overall situation.
Wish I could be more help, maybe somebody else will respond to your post with
a more helpful idea.
If I was you, this is what I'd do:
1) make sure the fan works normally without the new dimmer controller
2) inspect the wiring carefully when you install the controller to make sure it's correct, and
that you're not bypassing something you need to operate the circuit.
3) if I was sure I had all that done right, I'd look at contacting the mfgr for a recommendation
of what would work for what you want to do, or
4) try a different speed switch.
The counter emf from the fan motor might be interfering with the operation of some solid state device in your dimmer. Maybe you should use a switch that just uses resistors for speed control, instead of a dimmer circuit.
Good luck
