Can't interpolate curve or surface through points.

Hi,

I created a transform (contained in the group), which takes the points on a surface - in this case a cylinder - and maps them to new points using a kind of exponential mapping I came up with. You can see the mapped points inside the cylinder and the degree of the mapping is controlled by the slider 'alpha' which can vary between zero and one.

I have tried to take the resulting points and interpolate a curve through them, which gives me strange results and also to interpolate a surface through them, which gives me an error although I think I'm using the correct 'u+1' value.

I would appreciate any help here. I suspect it has to do with data structure, but when I look at the trees for point before and after, to my untrained eyes, they look the same. Thanks.