Where is my flaw in the following code?

```
(define (newtons-method2 f guess n)
(define (newton-transform f)
 (lambda (x)
  (- x (/ (f x) ((der f 0.5) x)))))
(let ((next (newton-transform guess)))
(if (= 0 n)
    next
    (newtons-method2 (f next (- n 1))))))

```

*The method is named "newtons-method2" because this was my second attempt at writing newton's method in scheme*

My derivative function is as follows: 

```
(define (der f h)
 (lambda (x)
 (/ (- (f(+ x h)) (f x))
    h)))

```