Spline Slide problem - can't get it to auto-align properly

hey guys,

I'm trying the Spline Slide tool for the first time, and I'm having a hard time getting it to align properly. I've put the file on dropbox here, if anyone would care to take a look:
https://dl.dropboxusercontent.com/u/17715/subdtest5.vws

When I turn auto-align off it properly follows the spline, but with it turned on it deviates from it and I can't for the life of me figure out why. I've tried making every point hard, naturalising the spline, deleting points to simplify it...
Nothing's done the trick so far.

The simple answer to your question is this: the pivot position of your shape-spline is far off.
Somehow the auto orient algorithm takes into account the relative position of the spline's pivot.

I found having the most predictable results when:
1. the starting CVs of the 2 splines coincide
2. the pivot position of the shape spline is at its starting CV

After setting up the spline slide tool, you can hit the E-Button to be able to still adjust the splines, so you get the result you are looking for. After you're done, you can execute "Finalize Spline Modifier".

Man that's fiddly! It's fantastic that it's non-destructive in a way, though. Hopefully Kun extends the non-destructive tools, as they're basically the only thing I miss from bigger packages. It's great to see here that they're at least technically possible.