HELP! Scheme!

So, I recently read about the collatz conjecture on xkcd.
Of course I had read my SICP that day (like every day), so I was
certain, I could easily implement it in Scheme. Like this:

(define (collatz n)
  ((display n)
   (newline)
   (if (> n 1)
       (if (odd? n) (collatz (+ (* 3 n) 1))
           (collatz (/ n 2)))
       1)))

When i call (collatz 10), for instance, PLT Scheme gives
me all the numbers, until it throws an error when it reaches 1:
procedure application: expected procedure, given: #<void>; arguments were: #<void> 1

How do I do it right?

...do you even know what parentheses denote in SICP Scheme outside from special forms?