Ritchie,

Just to make sure that you don't have anything plugged into the trigger jack. If you have a cable plugged into the trigger jack and it is not giving voltage the light will be red and the sub won't work. Once 12v or there abouts is applied to the trigger cable then light will go green and sub will work.

This only applies if you have a cable plugged into the trigger jack. If you don't then red probably indicates a problem.