63 - Shore Power hook up not activating

[AirstreamCDA]

Hi - I have just picked up a 63 Safari Double - and it has separate 12v and 120v dc (like two lights at each location, one for battery and one for 120). I plugged the trailer into shore power and my tester suggests that there is power at the plugs and light outlets but there does not appear to be (enough?) power to turn a light on. Is there a switch for shore power in the trailer somewhere? I cannot find a circuit box or fuse box on board - am I looking in the wrong places?

Usually there is a fuse box or circuit box but I cannot find anything. Any help would be very appreciated.

Thanks