Drawing Generative Bezier Curves

I am currently using trail renderer on an object which is following a spline using spline controller - http://www.unifycommunity.com/wiki/index.php?title=Spline_Controller to draw curved lines....
It seems that the calculations are made when the application starts because if I adjust the position of any of the control points after the game has started it doesn't effect the movement of the object.

Perhaps there is a better way of achieving what I am after or a way of getting it to work.

any ideas guys?

Cheers