Is there anything wrong with my "sum of list" code in scheme?

Question

My else statement line is giving me an error. Is any of my other line of codes affecting the else expression?

(define (sumAdd list)
  (cond
    ((null? list) '())
    ((null? (cdr list)) list)
    ((symbol? list) sumAdd(cdr list))
    (else (+ (car list)(sumAdd (cdr list))))
    )
  )