The lights are probably 12V and run from the battery supply and not shore power/generator. Lots of possible causes including 1) no transfer switch and shore power cord needs to be plugged into generator outlet 2) bad transfer switch 3) tripped breaker at power convertor or generator 4) generator to generating power. Is there an outlet you can plug shore power in to rule out everything related to generator? Assuming a 30amp shore cord, you can get adapters to plug into regular residential outlets but you won't have enough power to run A/C and major appliance. You should get enough to check for power though.