I am trying to create a polyline from a corridor feature line for bottom of the pavement.

From a 2D plan view we cannot select the feature line, so I moved to a 3D view & using orbit I was able to see the feature line (bottom of the pavement).

But when I try to use "Create Polyline from Corridor" & when I selected the feature line, it says selected entity is not a feature line.

Any one experienced this before.