Foundations Third Edition Odd "Helix" Behaviour

Hi,

I am coming back to Grasshopper after a hiatus. I am working my way through the Foundations Primer Third Edition. With the example: F.2.2.3 steps 1 through 21 I get the same results as illustrated in the book. But, with steps 22 through 24 I get a sine curve rotated 45 degrees on the x axis, not a helix. I assume I'm missing something simple.

Thanks,

Gene