Hi Mala,

re:
> Mirroring scale line, file.

Thanks, so yes when using the "scaling rail" function for sweep the way it works is it scales the profile curve using the point on the path curve as the scale origin. That will then produce shaping on both sides of the rail like you're seeing here.

You could try trimming the sweep with a plane to cut off the bottom half and then make a half cylinder for the bottom part separately.

But I'd recommend using the Loft with Loft style = "Loose" like I showed above instead:
http://moi3d.com/forum/index.php?webtag=MOI&msg=10120.12

If you're having difficulty with that method please post the 3dm model file for it so I can see what's going wrong.

- Michael