I am attempting to follow the lesson Winding a Cable (15-ENG-ANM-0003), but am stumped when my cable doesn't rebuild during animation. It is supposed to rebuild each frame and appear like it is winding from one reel to the other. It just moves instead.

What am I missing? It is probably a setting or a mate or something, but I thought I followed the lesson exactly.

I can rebuild my assembly at the end and get the correct visual, so I know my equations are correct.

Yet when I press "play from start" I get this, which isn't right either.