can't get smooth on vextex spline

Hello

I made a little script to make a spline between choosen vertex in reordered selected splines. It seems to works but I can't manage to turn vertexes final spline to smooth.
Can somebody help ?

" try destroyDialog rlMover catch()
global rlconnect = rollout rlconnect "Mover"
(
button butconnect "GO" pos:[2,2]
spinner spX "X " width:60 range:[1,100,1] type:#integer pos:[55,5]
on butconnect pressed do
(
ss = SplineShape pos:[0,0,0]
addNewSpline ss
names_array = for i in $ collect i.name
sort names_array
for a = 1 to names_array.count by 1 do
(
node_by_name = getNodeByName names_array[a]
selectMore node_by_name
knotPos = (getKnotPoint node_by_name 1 spX.value)
addKnot ss 1 #corner #line knotPos
)
updateShape ss
ss
)
)
createDialog rlconnect 160 25"