I think the only way for motion guides to work are is upon making the motion guide, you need to get a pen tool or a pencil tool, and draw it in one stroke, without letting go. I tried the same just last week. I tried using existing lines, but they didn’t work. I tried connecting a whole bunch of straight lines, but that didn’t work.
Hey man. it does work.
You have to break apart the existing line…
Then make sure to get the properties of thing you are moving across the guide…
Make sure it has Guided checked in the properties…
But that was the problem… the existing line has to be broken apart first…