Ford Duetto Cabin lights

None of the (3) Footwell lights come on when I open a door. There is a switch on the dashboard which the manual says operates the interior lights in the passenger compartment and which does light up when pushed. It doesn't seem to do anything else though. There are also 3 lights above the rearview mirror which all work, but the 20 second timer on the central light doesn't. Can anyone advise as the manual isn't much help.

I can't really help, other than to say that my Duetto's footwell lights work either; when I investigated the sliding door light, there was no bulb, or wiring to it.....

I am trying to think how the step lights were switched on our Duetto. I think it depended on the position of the switch next to the interior mirror. 
I found a few discrepancies because our Duetto was built on the Tourano. This was a German spec mini bus before the build conversion by Autosleepers.