Execute file compiled by sbcl cannot make random or make with-open-file work.

I write a script with using random and with-open-file, it works well in slime by emacs. But it cannot work when I use sbcl compile it to a execute file.

Code:

(defun choice-file-to-open (files)
  (let ((filePath (nth (random (length files)) files)))
    (open-by-system filePath)
    (with-open-file (file "./logs" :direction :output
                          :if-exists :append
                          :external-format '(:utf-8 :replacement #\?))
      (format file "~S~%" (namestring filePath)))))

open-by-system is a function to open file.

My purpose is pick random file in the folder. But it always choice the same file to open when I use it. Only for the singer execute file, the slime work well.

Then I add the log file to record the filename every time I open. But there is no log file, as same as problem before, this problem only issues in executed file, and code works well in slime.

I found the answer (Random) in Common Lisp Not So Random? and it cannot solve the random problem.

What wrong with me? There are many differences between slime and sbcl?