Well there are several things that could have gone wrong. First what size are you keeping the fish in. Comet's require 55 gallons each for full size (at least), while Shubunkins require 20 gallons for the first one plus 10 gallons for each additional one. Keep that in mind.
Second, when you say the correct amount of starter bacteria, what do you mean? First, most of these starter bacterias do not work at all. Second of all, even if they do work, if you added them and left them for a few weeks, they could have all died out from a lack of ammonia to feed on. If you want to go with bacteria, you need to pick one that works and then add it and add the fish right away, however that's risky. You should just fish-less cycle instead.
The last thing is shock. You need to make sure to introduce the fish slowly. What I do is first put the back in and let it sit for 15 minutes. Then I take out 1 tablespoon of water, discard it, and add a tablespoon of water from the aquarium. I keep doing that until the entire volume is replaced, and then I wait a few more minutes before letting the fish enter.
Oh yeah, and also remember that the water you put in the tank should be treated with prime for any potential chemicals.
