I'm trying to constrain the motion of a cylinder inside another cylinder.   I have a point in one part and a curve in the center of the 2nd part.  I can create a constraint using the point and curve (using coincident or path) but there are no limits.  I can drag the first part "off" the other part.  Shouldn't the part stop when the point reaches the end of the curve?

I found a similar example in another post and it works properly.  I can't figure out why mine is unconstrained.  See the image below where the point has separated from the curve.

Thanks,

Matt