parametric equation

Hi
Regarding my last post : http://forum.librecad.org/Cycloid-Suggestion-tt5715544.html

I try to succeed in drawing cycloïd with parametric equations :

50*t-0,5*50*sin(t)
50-0,5*50*cos(t)
T1 = 0
T2 = 10
Step = 6*pi

It should normally work, what’s wrong ?
Thanks