There is a known issue with the lighting section of the aircraft.cfg file of the PAD DHC6-400 that will cause night lighting to display incorrectly. Check the "LIGHTS" section of your aircraft.cfg file and ensure that it contains the following:

[LIGHTS]
//Types: 1=beacon, 2=strobe, 3=navigation, 4=cockpit
light.0=3, -30.72, 0.00, 0.90, fx_navwhi,
light.1=2, -0.276, -32.316, 5.154, fx_strobeh,
light.2=2, -0.276, 32.316, 5.154, fx_strobeh,
light.3=1, -28.44, 0.00, 13.21, fx_beaconh,
light.4=1, -14.6, 0.00, -2.0 , fx_beaconh,
light.5=4, 6.00, 0.00, 2.0 , fx_vclightwhite,
light.6=4, 3.00, 0.00, 2.0 , fx_vclightwhite,
light.7=4, -3.00, 0.00, 2.0 , fx_vclightwhite,
light.8=4, -7.00, 0.00, 2.0 , fx_vclightwhite,
light.9=3, -0.176, -32.316, 5.154, fx_navred
light.10=3, -0.176, 32.316, 5.154, fx_navgre

If not, copy/paste this configuration to replace the existing.

Adjusting light configuration kindly provided by Bob May, Premier Aircraft Design, in response to a support ticket submitted by Randy L. Whynacht on 1 October 2009.