How to let the D-Lighting work on Nikon D90? On the current setting it won't work?

D-lighting won't work on the current setting, how to let it work?

What is the current setting and why are you so sure that it's not working?

All of your answers are in the manual.

If your current setting is Auto you are not going to have much control. If you are not ready to jump into using A, S, or M, you can take a tentative step towards having a little more control by using P.