external script in <defunct> state

I wan to run external script when Acct-Stop packets received. My acct_users file: DEFAULT Acct-Status-Type == Stop Exec-Program = "/usr/local/sbin/testacct.php" Script runs and executes normally but stays in <defunct> state for every call: 5154 ? Z 0:00 [testacct.php <defunct>] 5159 ? Z 0:00 [testacct.php <defunct>] 5161 ? Z 0:00 [testacct.php <defunct>] ...... Where is the mistake can be?