Restrictor - missing a step?

[atomicandrea]

When I create a restrictor, I can select a path, but it appears grayed out in the Property Browser. The shape that I've created doesn't follow the path. What step am I missing?

[jtalaiver]

so you have to set the option for "Can Move" to "Along a Path"

Then click the triple dots next to Move Path and then you can select the line... check attached...