This array index is invalid for this array

hello

I am trying to replicate a relatively simple worksheet from:

http://www.alueurope.eu/talat/lectures/2301ex/ex81.pdf

I get the above mentioned error when typing the infromation about sectorial coordinates on the page 2. I have also attached the worksheet. How come it works for the author of the document but not for me? Is it because it is another version of MathCAD? If so how can I fix it?

Thanks in advance