The headlights are purposely put on redundant circuits after the switch for safety. If neither is getting power, it's likely that you're not getting power to the switch, though this should be easy to test. See excerpt below from RAVE electrical library. Recommend you have a look at the wiring diagram (available through google search) and follow the circuits from the lights to the power source/ground source.
Headlamps - Dip Beam Operation
When the lighting switch is moved to the headlamp position, the feed from fusible link 10 in
the engine compartment fusebox passes through the switch contacts. The feed is connected
on a UR wire to the passenger compartment fusebox, where it passes through fuses 9 and
10.
LH headlamp
The feed from fuse 9 is connected on a UK wire from the passenger compartment fusebox
to the LH headlamp and illuminates the LH dip beam bulb. The earth path from the LH
headlamp is connected on a B wire to earth eyelet connector C0564-1.
RH headlamp
The feed from fuse 10 is connected on a UB wire from the passenger compartment fusebox
to the RH headlamp and illuminates the RH dip beam bulb. The earth path from the RH
headlamp is connected on a B wire to earth eyelet connector C0559-1