Your first problem is that the trailer does not carry a catamaran sailboat!

Seriously though, an atypical rear trailer light bulb has two elements in it for two different signals; illumination (i.e. parking lights) and brake/turn signal. If you are getting neither a brake light or turn signal, it could be that the bulb is bad, the bulb is making a poor connection on one of it's contact points, the trailer connector is making a poor connection to the vehicle harness, or you have a bad wire somewhere.