這是什麼病症

A PHP Error was encountered

Severity: Notice

Message: Undefined index: replay_date

Filename: new_web/question_detail.php

Line Number: 102

Backtrace:

File: /var/www/html/pettalk/application/views/new_web/question_detail.php
Line: 102
Function: _error_handler

File: /var/www/html/pettalk/application/controllers/Question.php
Line: 240
Function: view

File: /var/www/html/pettalk/index.php
Line: 315
Function: require_once