sicp pls

http://www.pastebay.net/1154964
I used the filter function for ex 1.3 sicp . But it fails for equal numbers.Please help

(define (smallest a-list)
  (cond ((null? (cdr a-list))  (car a-list))
        ((<= (car a-list)   (smallest ( cdr a-list))) (car a-list))
        (else (smallest(cdr a-list)))))