Question: Why can't find critical point in all function ?

in try to figure out why in some function i can find this critical point for ploting i need that point , untill now i just find in one function and other i can't and my program not runing for other and really this is make problem for my invistigation i want to fixed that and i upload that file i did and that file i can't find it for , thanks for any help?

line-undone.mw

Line-1-Done.mw

Please Wait...