That's ok and i just went to go and try it with disstilled water and it doesn't work i go and put it in some tap water and it works so what's the deal is it just the disstilled water soen't have enough pressure or what?
If your ultrasonic fogger is anything like mine (and I'm assuming they're all pretty much the same) the water level has to be just the right level to make fog. Most have an automatic shut off for when they get too low, and they dont work when they have too much water.
Additionally, when using tap water, deposits can build up on the ceramic disk and can break the device, or at least compromise the disk.
Hope this helps!
Cj