LISP help *update: got it

[CTho9305]

What's wrong with this?

(setf pointi (nth i lis))

If I set lis to a list of ((1 2) (3 4)) and so on, and i to some integer, it works fine. But in my function, when I try to compile/run, I get:

Error: Function position must contain a symbol or lambda expression: (SETF POINTI (NTH I LIS))

edit: progn is the answer.