Kong can't output console logs and error logs, Can't find log message why?

Kong version :0.14.1
Kong debug-level startup : kong start --vv
Kong configuration :
kong.config

log_level = debug
proxy_access_log = logs/access.log
proxy_error_log = logs/error.log
admin_access_log = logs/admin_access.log
admin_error_log = logs/error.log

my code:

local log = require “kong.cmd.utils.log”

log.debug(“debug info:” … msg)

ngx.log(ngx.ERR, "[my-error-log] : " ,msg)

kong start --vv

resolved…