Thanks for contacting us. When using surfaces, RailClone always projects its geometry on the local Z axis, so to use it to create a wall you would need to rotate the RailClone object 90 degrees on the X axis or create it in a front or side viewport. I've attached a sample file to illustrate with two RailClone objects, one in the usual position on the XY plane, and another that has been rotated to create a wall. I hope they help.
You might also find this chapter on Surfaces
from our Next Steps with RailClone
guide useful as it goes over using surfaces in more detail.