Tumbling objects on path, won't follow correctly as children.

I tried using a roller coaster tut. that has children parented to the vertices of a subdivided plane. The plane uses a curve modifier and is moved via X translation values. Simple, and it works in the tut. In Blender 2.5 on my Mac the plane moves fine but the children tumble constantly. I’ve tried everything; different curve types; more constraints; etc.

It could be just too logical. The tut. plan had the outrigger verts swept back from the center (more forward) vert. Apparently this adds more stability, like an actual platform, and keeps the parented objects from flipping out. But, maybe not. Does anyone know for sure?

Did you use 1 or 3 points when you vertex parented to the plane? You get more stability if you use 3.

I used 3 the whole time, but they started off in a straight line. Now I’m trying to manipulate the child objects on the path, adjusting left and right (port and starboard). If I add another object in the parent hierarchy, I can adjust the child but key framing will not stick. Where ever I position the child, it stays. I wonder why this won’t keyframe?

I successfully used a translation constraint, but I could not get the constraint controls to work like a ‘local’ axis. Man, what a pain in the butt that was. I am surely doing this wrong.