Issue Draping Line Over Terrain

I am trying to drape a line over a topography map that I imported from AutoCAD. The terrain is already in 3d, but the line is 2d. I have read in some places where the terrain or line need to be exploded, but then I find others saying the opposite. I have tried both ways, but whatever I do, the computer acts like it is working, but then nothing has changed. The setback line is in the same place, and the topography is the same. Any help would be greatly appreciated.

Does the topography have faces or only contours? The Drape command needs faces to project on.


The topography has contours and faces. I figured out that the problem was
a setting in the line weight display settings. Thank you for your help.