rectangular piping problem- however normal piping does work....???

Hi, I have had a look at the discussions on here about rectangular piping, however I can't get it to work on my script. However the normal piping tool does work so i am confused about what I am doing wrong.

I have put the different attempts I have tried...

The other problem is that i am trying to make the trail fade using the gradient tool, but that doesn't seem to work either.

Thanks for any help