Racket(Scheme)错误:预期引用后的符号名称,但找到了一个部分

我在Dr. Racket Verion 5.3.6中运行此代码(The Little Schemer):

(define rember
(lambda (a lat)
(cond
  ((null? lat) (quote ()))
  (else 
   (cond
     ((eq? (car lat) a) (cdr lat))
     (else (cons (car lat) (rember a (cdr lat)))))))))

并引发错误:quote: expected the name of the symbol after the quote, but found a part在(quote ()))一部分.我在这做错了什么？