Try touching the lights themselves. You can switch them on that way and I haven't figured out how that interacts with the overhead switch kestrel refers to. If no joy, consult Mr Dealer in case there is some fault.
I had this issue when I collected my car. Confused them at the dealer too - turns out the interior lights use the headlights light sensors and only switch on when unlocking/opening the doors when its dark outside - i.e they don't come on in the day.