Test firmware proves that the SSC is getting power and the light connected to it are working.
It doesn't prove that the SSC is receiving information. I would check to see if the data lines in are solder correctly.
I am going to assume since the other SSCs work than the rest of your hardware is working (computer, dongle, hub)
So that just leaves the pigtail and wire in and the input side of the SSC, right?
Rick R.